Usually your pharmacist will translate the traditional abbreviations derived from Latin for you on your prescription bottle. If you wish to know what the prescription reads before you take it to the pharmacist, here is a listing of some of the most common abbreviations.
 

Abbreviation		Meaning		Latin derivation
ac		before meals		ante cibum
bid		twice a day		bis en die
gt		drop		gutta
hr		at bedtime		hora somni
od		right eye		oculus dexter
os		left eye		oculus sinister
pc		after meals		post cibum
po		by mouth		per os
prn		as needed		pro re nata
q 3 h		every three hours		quaque 3 hora
qd		every day		quaque in die
qid		four times a day		quater in die
tid		three times a day		ter in die