Medical plurals are a bit different from the standard, everyday English variety. There are a few rules that can help you derive a plural the medical way. Read on to familiarize yourself with the nuances of medical plural building.
Medical rules for forming plurals
Some rules for pluralizing medical terms are as follows, with examples of the rule and exceptions to the rule.
Medical Rule 1: Change the a ending to ae
In other words, vertebra becomes vertebrae.
By adding the e to the plural, the “aah” sound ending pronunciation becomes “eh.”
Axilla, axillae
Bursa, bursae
Conjunctiva, conjunctivae
Scapula, scapulae
Sclera, sclerae
Medical Rule 2: Change the um ending to a
The a at the end is pronounced “aah.”
Acetabulum, acetabula
Antrum, antra
Atrium, atria
Bacterium, bacteria
Diverticulum, diverticula
Labium, labia
Medium, media
Medical Rule 3: Change the us ending to i
The i at the end is pronounced “eye.”
Alveolus, alveoli
Bronchus, bronchi
Coccus, cocci
Embolus, emboli
Fungus, fungi
Glomerulus, glomeruli
Meniscus, menisci
Syllabus, syllabi (but syllabuses is also acceptable)
The exceptions to this rule include the following:
Corpus, corpora
Meatus, meatus (stays the same)
Plexus, plexuses
Viscus, viscera
Medical Rule 4: Change the is ending to es
The es is pronounced “eez.”
Analysis, analyses
Diagnosis, diagnoses
Exostosis, exostoses
Metastasis, metastases
Prognosis, prognoses
Testis, testes
The exceptions to this rule are
Epididymis, epididymides
Femur, femora
Iris, irides
Medical Rule 5: Change the ma or oma ending to mata
Carcinoma, carcinomata
Condyloma, condylomata
Fibroma, fibromata
Leiomyoma, leiomyomata
In the Rule 5 examples, the English plural is also acceptable: condylomas, carcinomas, leiomyomas, and fibromas.
Medical Rule 6: When a term ends in yx, ax, or ix, change the x to c and add es
Appendix, appendices
Calyx, calyces
Calix, calices (Strange but true, both are correct)
Thorax, thoraces
Medical Rule 7: When a term ends in nx, change the x to g and add es
Larynx, larynges
Phalanx, phalanges
Medical Rule 8: For Latin medical terms that consist of a noun and adjective, pluralize both terms
Condyloma acuminatum, condylomata acuminata
Placenta previa, placentae previae
Verruca vulgaris, verrucae vulgares
There are (of course!) some exceptions to all these rules:
Cornu, cornua
Pons, pontes
Vas, vasa
English rules of forming plurals
Many medical terms apply basic English rules for forming plurals. Thank goodness! You will no doubt recognize many of these common English language plural rules.
English Rule 1: Add an s
Bronchoscope, bronchoscopes
Disease, diseases
Endoscope, endoscopes
Finger, fingers
Vein, veins
English Rule 2: When a term ends in s, x, ch, or sh, add es
Crutch, crutches
Distress, distresses
Patch, patches
Stress, stresses
English Rule 3: When a term ends in y after a consonant, change the y to i and add es
Artery, arteries
Bronchoscopy, bronchoscopies
Endoscopy, endoscopies
Ovary, ovaries
Therapy, therapies
English Rule 4: When a term ends in o after a consonant, add nes
Comedo, comedones
Exceptions:
Embryo, embryos
Placebo, placebos