Discreet
Middle English: from Old French discret, from Latin discretus ‘separate’, past participle of discernere ‘discern’, the sense arising from late Latin discretio (see discretion). Compare with discrete.
wiktionary
From Middle English discrete, from Old French discret, from Latin discrētus, from past participle of discernere. Doublet of discrete.
etymonline
discreet (adj.)
late-14c., "morally discerning, prudent, circumspect, wise or judicious in avoiding mistakes," from Old French discret "discreet, sensible, intelligent, wise," from Latin discretus "separated, distinct," in Medieval Latin "discerning, careful," past participle of discernere "to separate, set apart, divide, distribute; distinguish, perceive," from dis- "off, away" (see dis-) + cernere "distinguish, separate, sift" (from PIE root *krei- "to sieve," thus "discriminate, distinguish").
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 took some pains to show it. Related: Discreetly.
