英语词源字典 - 在线词源网站

discreet (adj.)[discreet 词源字典]: mid-14c., "morally discerning, prudent, circumspect," from Old French discret "discreet, sensible, intelligent, wise," from Latin discretus "separated, distinct," in Medieval Latin "discerning, careful," past participle of discernere "distinguish" (see discern). Meaning "separate, distinct" in English is late 14c.

Spellings discrete and nativized discreet co-existed until after c. 1600, when discreet became the common word for "careful, prudent," and discrete was maintained in philosophy, medicine, music and other disciplines that remembered Latin and made effort to obey it. Related: Discreetly.[discreet etymology, discreet origin, 英语词源]
gab (v.): "talk much," 1786, probably via Scottish and northern England dialect from earlier sense "speak foolishly; talk indiscreetly" (late 14c.), from gabben "to scoff, jeer; mock (someone), ridicule; reproach (oneself)," also "to lie to" (late 13c.), from a Scandinavian source, such as Old Norse gabba "to mock, make fun of," and probably in part from Old French gaber "to mock, jest; brag, boast," which, too, is from Scandinavian. Ultimately perhaps imitative (compare gabble, which might have shaded the sense of this word). Gabber was Middle English for "liar, deceiver; mocker." Related: Gabbed; gabbing.
indiscreet (adj.): "imprudent, not discrete" (early 15c.) and indiscrete "not containing distinct parts" (c. 1600) are both from Latin indiscretus "unseparated; indistinguishable, not known apart," the former via an Old French or Medieval Latin secondary sense. From in- "not" (see in- (1)) + discreet. Related: Indiscreetly; indiscreetness.
temerity (n.): late 14c., from Latin temeritatem (nominative temeritas) "blind chance, accident; rashness, indiscretion, foolhardiness," from temere "by chance, at random; indiscreetly, rashly," related to tenebrae "darkness," from PIE root *teme- "dark" (cognates: Sanskrit tamas- "darkness," tamsrah "dark;" Avestan temah "darkness;" Lithuanian tamsa "darkness," tamsus "dark;" Old Church Slavonic tima "darkness;" Old High German dinstar "dark;" Old Irish temel "darkness"). The connecting notion is "blindly, without foreseeing."