"pertaining to historical coins and coinage," 1765, from French numismatique (late 16c.), from Latin numismat-, stem of numisma "coin, currency, stamp on a coin," from Greek nomisma "current coin, piece of money; usage," literally "what has been sanctioned by custom or usage," from nomizein "have in use, adopt a custom," from nomos "custom, law, usage," from PIE root *nem- "assign, allot; take." Earlier in the same sense was nummary (1650s), from Latin nummarius, from nummus "a coin." Numelarian (c. 1500) was a word for "money-changer," from Latin nummularius. Related: Numismatical (1716).
1520s, "liable to customs or dues;" c. 1600, "according to established usage, habitual," from Medieval Latin custumarius, from Latin consuetudinarius, from consuetitudinem (see custom (n.)). In Middle English it was a noun, "written collection of customs" of a manor or community. Earlier words for "according to established usage" were custumal (c. 1400, from Old French), custumable (c. 1300). Related: Customarily.
late 14c., "custom, usage," from Old French consuetude and directly from Latin consuetudo "a being accustomed, habit, usage," from consuetus, past participle of consuescere "to accustom," from assimilated form of com-, here perhaps an intensive prefix (see com-), + suescere "become used to, accustom oneself," related to suus "oneself" (from PIE *swe- "oneself;" see idiom).
Meaning "that which one is accustomed to, habitual association" is from 1803. Related: Consuetudinal; consuetudinary.
c. 1300 as an adverbial phrase, "completely, thoroughly, to the utmost degree," from out (adv.). Adjective usage is attested by 1813.