An Etymological Dictionary of Astronomy and Astrophysics

The best or most favorable point, degree, amount, etc. The greatest degree or best result obtained or obtainable under specific conditions.

Etymology (EN): From L. optimum, neuter singular of optimus “best” (used as a suppletive superlative of bonus “good”).

Etymology (PE): Behiné, from behin superlative of beh “good, fine” (Mid.Pers. veh “better, good;” O.Pers. vahav-, vahu-; Av. vah-, vohu- “good;” cf. Skt. vasu- “good;” Hittite wasu-; Gaulish vesus “good”) + -in superlative suffix + -é nuance suffix.