FORMING PLURALS IN GENERAL
1. Most singular nouns are made plural just by adding s:
patient, patients; bone, bones; tendon, tendons;
symptom, symptoms; friend, friends; nurse, nurses;
doctor, doctors.
2. To form the plurals of nouns ending in s, x, ch, sh, and
z, add es: dress, dresses; church, churches; tax, taxes;
wish, wishes; process, processes; phalanx, phalanxes;
larynx, larynxes.
3. Singular nouns ending in y preceded by a vowel form
their plurals by adding s: attorney, attorneys; boy,
boys; x-ray, x-rays; key, keys.
4. Nouns ending in y preceded by a consonant form the
plural by changing y to i and adding es: policy,
policies; copy, copies; allergy, allergies; extremity,
extremities; study, studies; dichotomy, dichotomies;
deficiency, deficiencies.
5. Singular nouns ending in f and fe form the plural in
two ways. If the final f in the plural form is heard, add
s: belief, beliefs; safe, safes; and staff, staffs. If the
final f in the plural has a v sound, change the f to v and
add es: life, lives; half, halves; wife, wives; leaf, leaves.
6. Singular nouns ending in o preceded by a vowel form
their plurals by adding s: studio, studios; duo, duos;
and portfolio, portfolios. Singular nouns ending in o
preceded by a consonant form the plural by adding s or
es: echo, echoes; hero, heroes; two, twos; potato,
potatoes. Usage varies, so consult a dictionary when in
doubt. Note that there are two acceptable plurals of
zero (zeros, zeroes), and no (nos, noes).
FORMING PLURALS OF MEDICAL TERMS
(SEE THE BOOK, MAGLIE R. (2009) UNDERSTANDING
THE LANGUAGE OF MEDICINE, ROMA: ARACNE, PG. 80)