1550s, "action of enumerating," from Middle French énumération, from Latin enumerationem (nominative enumeratio) "a counting up," noun of action from past participle stem of enumerare "to reckon up, count over, enumerate," from assimilated form of ex- "from" (see ex-) + numerare "to count, number," from numerus "number" (see number (n.)). Meaning "a list, catalogue" is from 1724.