bid
Twice a day; every 12 hours
Ad. lib.
As much as wanted; freely
qd
Every day
ac
Before meals
prn
As needed; according to circumstances
qid
Four times a day; every 6 hours
qh
Every hour
pc
After meals
tid
Three times a day; every 8 hours
gtt
Drops
po
Per os (by, through the mouth)
NPO
nothing by mouth (no food or water)
tab
Tablet
GI
Gastrointestinal
SG
Specific Gravity
Ua or U/A
Urinalysis
IV
Intravenous
IM
Intramuscular
SQ or SubQ
Subcutaneous
IP
Intraperitonial
ID
Intradermal
IO
Intraosseous
IC
Intracardiac
ml
Milliliter