Plural forms of abbreviations
For most abbreviations, form the plural by adding s to the singular form.
bldg. / bldgs.
No. / Nos.
apt. / apts.
Dr. / Drs.
For uppercase abbreviations, including acronyms, form the plural by adding an s.
ABC / ABCs
WBC / WBCs
PhD / PhDs
VIP / VIPs
RN / RNs
For the sake of clarity, lowercase letters and abbreviations are pluralized by adding an apostrophe plus s ('s).
dotting the i's
wearing pj's
p's and q's
wbc's
rbc"s
Form plurals of brief or slang terms by adding an s.
exam / exams
poly / polys
lymph / lymphs
lab / labs
When words taken from other parts of speech are used as nouns, the plural is usually formed by the addition of s or es.
ifs, ands or buts
yeses and nos
dos and dont's
ins and outs
ups and downs
pros and cons
haves and have-nots
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