How do you work out the meaning of a biological word?

Split the word into its parts — prefix, root and suffix — then read it from the back to the front. The suffix (ending) often tells you what type of word it is; the root carries the core meaning; the prefix adds information about number, position, size or direction. Work out each part, then reassemble them. For example, diazotrophic = di (two) + azo (nitrogen) + troph (feed) + ic (adjective) = describing something that feeds on nitrogen gas.

What is the difference between a prefix, a root and a suffix?

A prefix goes at the start of a word and adds information such as number, size, position or direction (e.g. hyper- = too much). A root is the core of the word and carries its essential meaning (e.g. troph = feed). A suffix goes at the end and often tells you the type of word — an adjective, an enzyme, a cell or a condition (e.g. -ase = an enzyme, -itis = inflammation).

Why should you read biological words back to front?

Reading from the end first lets you identify the suffix (which tells you the type of word), then the root (the core meaning), then the prefix (the extra detail). Building the meaning up in that order makes long, unfamiliar words much easier to decode than reading them left to right.

Is learning biological word-parts useful for exams?

Yes. Knowing common prefixes, roots and suffixes lets you work out the meaning of unfamiliar terms in an exam without having memorised every word, and helps you avoid mixing up similar-looking terms such as hyperglycaemia and hypoglycaemia, or endocytosis and exocytosis.

AQAOCR AOCR BEdexcel AEdexcel BEdexcel Int’lWJEC / Eduqas

How to understand the meaning of biological terms

A-level Biology is full of long, strange-looking words — diazotrophic, hyperglycaemia, xerophyte, phototropism. Yet every one is logically built up from a few dozen word-parts. Learn the secret — divide and conquer, and read back to front — and unfamiliar terms lose their mystery. This page gives you the method, searchable tables of the parts, and an interactive decoder to practise on.

The method Anatomy of a word Word decoder Worked examples Word-part tables Every exam board Puzzles Quick quiz

The secret: divide and conquer

The secret of reading any biological word is to split it into its parts, work out what each part means, then reassemble them. Long words are not memorised one by one — they are decoded.

Where do you start? Not the front. The easiest way is to start at the end and work towards the beginning — read the word back to front. Each part does a different job:

The three jobs

Suffix (the ending) — often tells you the type of word: an adjective (-ic), an enzyme (-ase), a cell (-cyte), a condition (-itis).
Root (the middle) — carries the essence of the word, the crucial clue to what it is about (troph = feed, haem = blood).
Prefix (the start) — adds information about number, size, position, direction or degree (hyper- = too much, di- = two).

Roots often change slightly to help words join up — an -o- is added (haem→haemo), or a letter is dropped (haem→aem in anaemia). The meaning stays the same.

Anatomy of a word

Take endocytosis. Split it, read the parts, reassemble — and a scary word becomes simple.

endo-

prefixinside / into

cyt

rootcell

-osis

suffixprocess

Reassembled: the process of taking material into the cell. Swap the prefix for exo- (outside) and you have exocytosis — moving material out. One part changes; the meaning flips.

Interactive word decoder

Pick a prefix, a root and a suffix to build a real A-level Biology word — and see it decoded into its meaning. As you choose, the other menus keep only the parts that complete a real word, so everything you build is genuine. There are real words to discover.

Prefix

Root

Suffix

Every combination the menus allow is a real biological word. Try starting from the root — it carries the core meaning.

Worked examples: read it back to front

Click each word to see it decoded from the end to the beginning, then reassembled — exactly the method to use in the exam.

diazotrophicread it back to frontthe article’s word

-icsuffixtells us it is an adjective (a describing word). The matching noun is diazotroph.
trophrootmeans feed / nourish — so the word is about feeding.
azorootrefers to nitrogen (from azote, the old name for the ‘lifeless gas’).
di-prefixmeans two — two nitrogens, i.e. N₂ gas.

Putting it together: Reading back to front then reassembling: an organism that feeds on nitrogen gas (N₂). That is a diazotroph — for example, the nitrogen-fixing bacteria in root nodules.

arthropodread it back to fronttry it yourself

(no verb/adjective suffix)suffixthere is no adjective or verb ending, so the word is a noun — the name of a thing.
podrootmeans foot (think of a tripod — three feet).
arthro-rootmeans joint (think of arthritis — a disease of the joints).

Putting it together: Reassembling: jointed feet. An arthropod is an animal with jointed legs — a crab, spider, insect or centipede.

hyperglycaemiaread it back to frontan exam favourite

-aemiasuffixmeans a condition of the blood (the same haem root for blood, having lost its h).
glycrootmeans sweet / sugar (as in glycogen).
hyper-prefixmeans too much / above normal.

Putting it together: Put together: too much sugar in the blood — a high blood-glucose condition, the opposite of hypoglycaemia.

The word-part tables

The most useful biological prefixes, roots and suffixes, grouped by meaning. Search the whole bank, or open a group to browse it. Every entry has an example so you can see the part in a real word.

No word-parts match your search. Try a shorter term.

How many? How big?35 word-partsPrefix

Prefixes about number, size and amount. They go at the start of a word and add information without changing what type of word it is.

Word-part	Meaning	Example
a-, an-	without / not	anaerobic — without air (oxygen)
bi-	two	bicep — muscle with two heads
centi-	hundredth	centimetre — one hundredth of a metre
deca-	ten	decapod — ten-footed (crabs, prawns)
deci-	tenth	decibel — one tenth of a bel
demi-	half	demilune — half-moon shaped
di-	two / double	disaccharide — sugar made of two units
diplo-	double	diploid — two sets of chromosomes
duo-	two	duodenum — first part of the small intestine
giga-	billion (10⁹)	gigabase — one billion base pairs
haplo-	single	haploid — one set of chromosomes
hect-, hecto-	hundred	hectare — ten thousand square metres
hemi-	half	hemisphere — half a sphere
hetero-	different	heterozygous — two different alleles
hex-	six	hexose — six-carbon sugar
homo-	same	homozygous — two identical alleles
iso-	equal / same	isotonic — of equal solute concentration
kilo-	thousand	kilojoule — one thousand joules
macro-	large	macromolecule — a very large molecule
magni-	large	magnify — to make larger
mega-	large / million	megakaryocyte — a very large cell
micro-	small / millionth	microscope — tool for viewing small things
milli-	thousandth	millimetre — one thousandth of a metre
mono-	one	monosaccharide — single sugar unit
multi-	many	multicellular — made of many cells
nano-	billionth (10⁻⁹)	nanometre — one billionth of a metre
oct-	eight	octopus — eight-footed animal
oligo-	few	oligosaccharide — a few sugar units joined
pent-	five	pentose — five-carbon sugar
poly-	many	polysaccharide — many sugar units joined
quadr-	four	quadrat — square sampling frame
semi-	half	semipermeable — partially permeable
tetr-	four	tetrapod — four-limbed vertebrate
tri-	three	trisaccharide — three sugar units
un-	one	unicellular — made of one cell

Where? When? Which way?38 word-partsPrefix

Prefixes about position, direction and time — above/below, inside/outside, before/after, towards/away.

Word-part	Meaning	Example
ab-	away from	abduct — to move away from the midline
ad-	towards	adduct — to move towards the midline
ana-	up	anabolism — building up of molecules
ante-	before	antenatal — before birth
anti-	against	antibody — acts against a pathogen
apo-	separate / away	apoptosis — programmed cell death
cata-	down	catabolism — breaking down of molecules
circum-	around	circumference — distance around a circle
com-, con-	with / together	convergent — coming together
contra-	opposite	contraception — against conception
dextro-	right	dextrose — right-rotating sugar
dia-	through / across	diffusion — spreading through
ecto-	outside	ectoparasite — parasite on the outside
endo-	within / inside	endocytosis — taking into the cell
epi-	upon / above	epidermis — outer layer upon the skin
eu-	good / true / well	eukaryote — cell with a true nucleus
ex-, exo-	out of / outside	exocytosis — moving out of the cell
extra-	beyond / outside	extracellular — outside the cell
hyper-	above / too much	hyperglycaemia — too much blood glucose
hypo-	beneath / too little	hypothalamus — below the thalamus
infra-	under / below	infrared — below red in the spectrum
inter-	between	intercostal — between the ribs
intra-	within	intracellular — within the cell
laevo-	left	laevorotatory — left-rotating
meso-	middle	mesophyll — middle tissue of a leaf
meta-	after / change	metabolism — the body’s chemical changes
para-	near / beside	parathyroid — beside the thyroid
per-	through	permeable — allowing passage through
peri-	around	pericardium — membrane around the heart
post-	after	post-synaptic — after the synapse
pre-	before	pre-synaptic — before the synapse
pro-	in front of / before	prophase — first phase of mitosis
retro-	behind / backwards	retrovirus — runs its cycle backwards
sub-	below / under	sublingual — under the tongue
super-, supra-	above / beyond	supraorbital — above the eye socket
sym-, syn-	with / together	synthesis — putting together
trans-	across	transpiration — water loss across a leaf
ultra-	beyond	ultrafiltration — filtration under high pressure

What colour?11 word-partsPrefix

Colour word-parts. Many appear in the names of pigments, blood cells and organisms.

Word-part	Meaning	Example
alb-	white	albino — lacking pigment (white)
chlor-	green	chlorophyll — green leaf pigment
chrom-	colour	chromosome — coloured body in the nucleus
chrys-	golden	chrysanthemum — golden flower
cyan-	blue	cyanobacteria — blue-green bacteria
erythr-	red	erythrocyte — red blood cell
flav-	yellow	flavonoid — a yellow plant pigment
leuc-, leuk-	white	leucocyte — white blood cell
melan-	black	melanin — dark skin pigment
rhodo-	red / rose	rhododendron — rose-coloured tree
xanth-	yellow	xanthophyll — yellow leaf pigment

Chemical store13 word-partsRoot

Roots for the biological molecules — sugars, fats, starch and water — that fill your specification’s biochemistry topics.

Word-part	Meaning	Example
adip-	fat	adipose — fat-storing tissue
amyl-	starch	amylase — starch-digesting enzyme
aqua-, aquo-	water	aquatic — living in water
gluco-, glucos-	glucose	glucose — a six-carbon sugar
glyc-	sweet / sugar	glycogen — animal sugar store
hydr-	water	hydrolysis — splitting with water
ket-	ketone	ketone — product of fat breakdown
lact-	milk	lactose — milk sugar
lign-	wood	lignin — woody strengthening in xylem
lip-	fat	lipid — a fat or oil
-ose	sugar	sucrose — table sugar
sacchar-	sugar	monosaccharide — single sugar unit
sucr-	sugar	sucrase — sucrose-digesting enzyme

The body23 word-partsRoot

Roots naming the parts of the body — organs, tissues and structures.

Word-part	Meaning	Example
acr-	extremities / tip	acrosome — tip of a sperm cell
angio-	vessel	angiosperm — plant with vessels / enclosed seeds
arthro-	joint	arthropod — animal with jointed legs
cardi-	heart	cardiac — relating to the heart
ceph-	head	cephalopod — head-footed animal (squid)
corp-	body	corpuscle — a small body / cell
cost-	rib	intercostal — between the ribs
derm-	skin	dermis — the layer beneath the epidermis
dors-	back	dorsal — relating to the back
gastr-	stomach	gastric — relating to the stomach
glob-	round / ball	haemoglobin — round blood protein
karyo-	nucleus	eukaryote — cell with a true nucleus
myo-	muscle	myofibril — muscle fibre unit
neur-	nerve	neurone — a nerve cell
opt-	eye	optic — relating to the eye
oss-	bone	ossify — to turn to bone
ped-, pod-	foot	pseudopod — false foot
pil-	hair	pilus — hair-like projection
pulmo-	lung	pulmonary — relating to the lungs
scler-	hard	sclerenchyma — hard support tissue in plants
som-	body	chromosome — coloured body in the nucleus
vas-	vessel	vascular — containing vessels
ventr-	belly / front	ventral — relating to the underside

Roots for every occasion62 word-partsRoot

The big list of general biological roots. The root carries the core meaning — the essential clue to what a word is saying.

Word-part	Meaning	Example
amphi-	both	amphibian — lives in water and on land
andr-	male / man	androgen — male hormone
aster-	star	aster — star-shaped spindle structure
auto-	self	autotroph — self-feeder (makes own food)
aux-	grow	auxin — plant growth hormone
avi-	bird	avian — relating to birds
bio-	life	biology — the study of life
-biotic	living	antibiotic — acts against living microbes
brachy-	short	brachydactyly — short fingers
brady-	slow	bradycardia — slow heart rate
branch-	gill	branchial — relating to gills
bursa-	pouch	bursa — a fluid-filled pouch
calor-	heat	calorimeter — measures heat energy
carp-	fruit / seed	carpel — female part of a flower
chondr-	cartilage / granule	chondrocyte — cartilage cell
crypt-	hidden	cryptic — camouflaged / hidden
cyst-	capsule / bladder	cyst — a fluid-filled sac
cyt-	cell	cytoplasm — the fluid inside a cell
dendr-	tree	dendrite — branching part of a neurone
echin-	spiny	echinoderm — spiny-skinned animal (starfish)
gam-	marriage / gamete	gamete — a sex cell
gen-	produce / origin	gene — unit of inheritance
glia-	glue	neuroglia — supporting cells of the nerves
gono-	seed / reproductive	gonad — sex organ
gymn-	naked	gymnosperm — plant with naked seeds
gyn-	female / woman	gynoecium — female parts of a flower
haem-, -aem-	blood	haemoglobin — oxygen-carrying blood protein
hom-, anthrop-	man / human	anthropology — the study of humans
hyal-	glassy / clear	hyaline — clear, glass-like cartilage
lacuna-	space / gap	lacuna — a small cavity
lumen-	cavity	lumen — the space inside a tube
lys-, -lysis	loosen / break	haemolysis — breaking of red cells
macula-	spot	macula — spot on the retina
mito-	thread	mitochondrion — thread-like organelle
morph-	form / shape	morphology — the study of form
neo-	new	neonate — a newborn
oo-	egg	oocyte — an immature egg cell
phag-	eat	phagocyte — cell that engulfs (eats)
phil-	loving / liking	hydrophilic — water-loving
phor-, pher-	carry	phloem — carries sugars (bearer)
phot-	light	photosynthesis — making food using light
phragm-	fence / wall	diaphragm — the wall below the lungs
phyll-	leaf	mesophyll — the middle leaf tissue
phyt-, phyto-	plant	epiphyte — a plant growing on a plant
pisc-	fish	piscivore — a fish-eater
platy-	flat	platyhelminth — flatworm
pleur-	side / rib	pleural — relating to the lung lining
pneu-	air / lung	pneumatophore — an air-breathing root
pseud-	false	pseudopod — false foot
radi-	ray / root	radicle — the first root of a seedling
rect-	straight	rectum — the straight end of the gut
rhiz-	root	rhizome — an underground stem
schiz-	split	schizocarp — a fruit that splits
sperm-	seed	gymnosperm — naked-seed plant
sten-	narrow	stenosis — narrowing of a vessel
therm-	heat	thermoregulation — control of body heat
troph-	feed / nourish	autotroph — self-feeder
trop-	turn / respond	phototropism — growth turning to light
vitr-	glass	in vitro — in glass (in the lab)
xer-	dry	xerophyte — a plant adapted to dry places
zo-, zoo-	animal	zoology — the study of animals
zyg-	yoke / joined	zygote — cell formed when gametes join

Word endings (suffixes)19 word-partsSuffix

Suffixes go at the end of a word. They often tell you the type of word (adjective, enzyme, cell, condition) as well as adding meaning.

Word-part	Meaning	Example
-al	relating to (adjective)	skeletal — relating to the skeleton
-ic	relating to (adjective)	genetic — relating to genes
-ive	tending to (adjective)	digestive — tending to digest
-ous	full of (adjective)	cancerous — full of / like cancer
-ful	full of (adjective)	harmful — full of harm
-less	without (adjective)	seedless — without seeds
-able, -ible	able to be (adjective)	permeable — able to be passed through
-ase	an enzyme (noun)	lipase — a fat-digesting enzyme
-ose	a sugar (noun)	glucose — a sugar
-cyte	a cell (noun)	leucocyte — a white blood cell
-oma	a tumour / swelling	carcinoma — a cancerous tumour
-itis	inflammation of	hepatitis — inflammation of the liver
-osis	a condition / process	osmosis — the process of osmosis
-lysis	breakdown / splitting	hydrolysis — splitting using water
-troph, -trophic	feeding (on)	autotrophic — self-feeding
-phyte	a plant	xerophyte — a plant of dry places
-pod	a foot	arthropod — a jointed-foot animal
-rrhage	to burst / flow out	haemorrhage — a heavy loss of blood
-rrhoea	to flow	diarrhoea — flowing (of the gut)

Why this helps in every exam board

Every A-level Biology specification is written in this vocabulary. None of them give you a glossary in the exam — so being able to decode an unfamiliar term on the spot is worth marks across all of them.

Board	Where word-decoding helps
AQA (7402)	Unfamiliar organisms and molecules in data questions; defining terms precisely (e.g. hydrolysis, antibiotic) rather than describing them vaguely.
OCR A (H420)	Application questions using novel contexts and named structures; recognising -lysis, -trophic, iso-/hyper-/hypo- in osmosis and transport.
OCR B – Advancing Biology (H422)	Context-led questions with unfamiliar species and conditions; decoding medical and ecological terms from their parts.
Edexcel A – SNAB (9BN0)	Applied, issue-based questions where new terminology appears; distinguishing look-alike terms such as endo-/exocytosis.
Edexcel B (9BI0)	Precise use of biochemical vocabulary (-ose, -ase, glyc-, lip-) in structured and extended answers.
Edexcel International (YBI11)	Wide range of named organisms and processes; building meaning from roots when a term is not one you have met.
WJEC / Eduqas	Defining and distinguishing terms in short-answer questions; medical and physiological vocabulary (hyper-/hypo-, -aemia, cardi-, pulmo-).

Puzzles: practise decoding

Five ways to test yourself — choose a puzzle below. Use the word-part tables above if you get stuck.

The one thing to remember

Divide · read back to front · reassemble

Split the word into prefix + root + suffix, start from the end, work out each part, and put the meaning back together. Do that and you can read biological words you have never seen before — in your notes, in a textbook, and in the exam.

Many word-parts also turn up in everyday words — antidote, bicycle, democracy, economics, helicopter, kilometre, rhinoceros, television. If you can read those, you already know more biological vocabulary than you think.

← Back toA-level Biology resources Also seeStatistics for A-level Biology ToolA-level Biology calculator