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mid-13c., "not alike" (sense now in diverse); late 13c., "separate, distinct; various," from Old French divers (11c.) "different, various, singular, odd, exceptional, wretched, treacherous, perverse," from Latin diversus "turned different ways," in Late Latin "various," past participle of divertere (see divert).
Sense of "several, numerous" is recorded from c.1300, referring "originally and in form to the variety of objects; but, as variety implies number, becoming an indefinite numeral word expressing multiplicity" [OED], a sense that emerged by c.1400.