Forming plurals of foreign nouns and terms
Many nouns of foreign origin retain their foreign plurals; others have been given English plurals, and still others have two plurals (an English and a foreign one). The medical lexicography is heavily influenced by terms derived from Greek and Latin, along with a smattering of French, German and other languages.
There are general rules for pluralizing Greek and Latin terms, but consult the current edition of an accepted medical dictionary for additional information.
The plural of words ending in -en is formed by changing the -en to -ina.
foramen / foramina
lumen / lumina
Form the plural of words ending in -a by adding an -e. Do not confuse this with words ending in -ma (as opposed to just -a).
plura / plurae
conjunctiva / conjunctivae
vertebra / vertebrae
bursa / bursae
bulla / bullae
Form the plural of words ending in -ma by retaining the -ma and adding -ta.
condyloma / condylomata
adenoma / adenomata
Form the plural of words ending in -us by changing -us to -i.
bronchus / bronchi
embolus / emboli
meniscus / menisci
nucleus / nuclei
calculus / calculi
EXCEPTIONS: There are some terms where the plural and the singular forms are the same.
meatus / meatus
processus / processus
Form the plural of words ending in -on by changing -on to -a.
ganglion / ganglia
criterion / criteria
phenomenon / phenomena
spermatozoon / spermatozoa
The plural of words ending in -is is formed by changing the -is to -es.
diagnosis / diagnoses
prognosis / prognoses
anastomosis / anatomoses
metastasis / metastases
prosthesis / prostheses
EXCEPTIONS: If you are unfamiliar with a term, check the medical dictionary for exceptions.
arthritis / arthritides
epididymis / epididymides
Form the plural of words ending in -um by changing -um to -a.
bacterium / bacteria
diverticulum / diverticula
ovum / ova
epithelium / epithelia
Form the plural of words ending in -ix or -ex by changing those endings to -ices.
apex / apices
index / indices
varix / varices
appendix / appendices
cortex / cortices
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