Medical terminology Unit Clerk (Formation of plurals) Chapter 1

Worlds ending in -a retain the -a and add -e:

Singular / Plural / (Meaning)
Vertebra / Vertebrae / (Backbones)
Bursa / Bursae / (Sacs of fluid near a joint)

Words ending in -is drop the -is and add -es:

Singular / Plural / (Meaning)
Diagnosis / Diagnoses / (Determination of the nature and causes of diseases)
Psychosis / Psychoses / (Abnormal condition of the mind)

Words ending in -ex or -ix drop the -ex or -ix and add -ices:

Singular / Plural / (Meaning)
Apex / Apices / (Pointed ends of organs)
Cortex / Cortices / (Outer parts of organs)
Varix / Varices / (Enlarged, swollen veins)

Worlds ending in -on drop the -on and add -a:

Singular / Plural / (Meaning)
Ganglion / Ganglia / (Group pf nerve cells; benign cysts near a joint (such as the wrist))

Words ending in -um drop the -um and add -a:

Singular / Plural / (Meaning)
Bacterium / Bacteria / (Types of one-celled organisms)
Ovum / Ova / (Egg cells)

Words ending in -us drop the -us and add -i:

Singular / Plural / (Meaning)
Bronchus / Bronchi / (Tubes leading from the windpipe to the lungs)
Calculus / Calculi / (Stones)