o.d. (Noun) — The right eye.
o.d. (Noun) — A doctor's degree in optometry.
o.d. (Noun) — A force or natural power supposed by Reichenbach and others to be manifest in magnets, heat, light, chemical or vital action, etc..
o.d. (Verb) — Dose too heavily.
o.d. (Interjection) — Used to express surprise.