Appendix B. 
Selected List of Latin Pharmaceutical  Abbreviations
Abbreviation Usage Meaning Latin Term
ac Before meals Ante Cibum
AD Right ear Auris Dextra
ad upto  
ad lib As Desired Ad Libitum
AS Left ear Auris Sinistra
Au Each ear Auris Utro
bid Twice a Day Bis in Die) (Die pronounced "DEE")
c with line over it With Cum
D. Dispense Dispensa (in subscription),
DTD dispense such doses Dentur tales doses No., (in subscription)
gtt Drop gutta
H.S. at Bedtime Hora Somni
IVPB Intravenous Intermittent Bolus  
IVP Intravenous Push  
NR Do not repeat Non Repetatur, (for refills)
OD Right Eye Oculus Dexter
OS Left Eye Oculus Sinister
OU Each Eye Oculus Uterque
pc After meals Post Cibos
po Orally Per Os
prn As needed Pro Re Nata
q Every Quaque
q.d. Every day Quaque Die (don't use-may look like q.i.d)
q_h Every _ Hours (ex. q 8h) Quaque _ Hora
QID Four times a Day Quarter in Die
qs ad Quantity sufficient to make

Example: total ingredients= 12 ml, qs ad 15 ml (add water to make final volume 15 ml).

Quantum sufficit Ad
s with line over it Without Sine
Sig. Mark thou Signa (as in instructions to the patient)
ss with line over it One Half Semis
STAT Immediately Statim
TID Three times a Day Ter in Die
TPN Total Parenteral Nutrition  
u.d As Directed Ut Dictum (Do not use this abbreviation!)


Also: Refer to P. Lofholm and B. Katzung, Rational Prescribing and Prescription Writing, pp 1007 In, B. Katzung, Basic and Clinical Pharmacology, Lange Medical Books/McGraw-Hill,New York,  2001.