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productive (adj.)[productive 词源字典]: 1610s, from French productif (16c.) and directly from Medieval Latin productivus "fit for production," from Latin product-, past participle stem of producere (see produce (v.)). Related: Productively; productiveness.[productive etymology, productive origin, 英语词源]
quasi-: word-forming element used since 18c. (but most productively in 20c.) and typically meaning "kind of, resembling, like but not really, as if;" from Latin quasi "as if, as it were" (see quasi).
unproductive (adj.): 1756, from un- (1) "not" + productive (adj.). Related: Unproductively; unproductiveness.