optimum (n.)

1879, from Latin optimum, neuter singular of optimus "best, very good" (used as a superlative of bonus "good"), perhaps (Watkins) related to ops "power, resources" (in which case the evolution is from "richest" to "the most esteemed," thus from PIE root *op- "to work, produce in abundance"); or perhaps it is related to ob "in front of" (de Vaan), with superlative suffix *-tumos.

In English the word was used originally in biology, in reference to "conditions most favorable" (for growth, metabolic processes, etc.). As an adjective, "best or most favorable," from 1885.

updated on September 13, 2019