c. 1300 as an adverbial phrase, "completely, thoroughly, to the utmost degree," from out (adv.). Adjective usage is attested by 1813.
1844, "to act as an optimist, take the most hopeful view of a matter," a back-formation from optimist. Meaning "to make the most of, develop to the utmost" is attested by 1857. Related: Optimized; optimizing.
c. 1500, "complete, perfect, carried to the utmost extent or degree," from Latin consummatus "perfected, complete," past participle of consummare "sum up, complete," from assimilated form of com "together, with" (see con-) + summa "sum, total," from summus "highest" (see sum (n.)). Of persons, "accomplished, very qualified," from 1640s. Related: Consummately.