An Etymological Dictionary of Astronomy and Astrophysics

1. The science that investigates the principles governing correct or reliable inference.
   

2. The system or principles of reasoning applicable to any branch of knowledge or study.
   

3. A particular method of reasoning or argumentation.

Etymology (EN): M.E. logik; O.Fr. logique, from L. (ars) logica, from Gk. logike (techne) “reasoning (art),” from feminine of logikos “pertaining to speaking or reasoning,” from logos “reason, idea, word.”

Etymology (PE): Guyik, from guy- present stem of goftan “to say, speak, relate, tell; to compose a poem,” from Mid.Pers. guftan “to say, tell, utter;” O.Pers. gaub- “to say” + -ik, → -ic.
Cemguyik, from Mid.Pers. cimgôwâgih “logic,” from cim “cause, reason, meaning” (Proto-Iranian *cahmāt “what for;” cf. Skt. kasmāt “why, where from,” kim “what”)

• gôwâgih Mod.Pers. guyi, as above.