femme fatale n.

mid-14c., "of the female sex," from Old French femenin (12c.) "feminine, female; with feminine qualities, effeminate," from Latin femininus "feminine" (in the grammatical sense at first), from femina "woman, female," literally "she who suckles" (from PIE root *dhe(i)- "to suck"). The usual modern sense of "woman-like, proper to or characteristic of women" is recorded from mid-15c. Related: Femininely.

The interplay of meanings now represented roughly in female "characteristic of the sex that bears children," feminine "having qualities considered appropriate to a woman," and effeminate "having female qualities in a bad sense, unmanly," and the attempt to keep them clear of each other, has led to many coinages. Among nouns, in addition to feminity "womanishness," femininity, femaleness, feminineness (1810, "female qualities"), there is feminitude (1878); feminility "womanliness" (1824); feminie "womankind" (late 14c.); femality (17c., "effeminacy;" 1754 "female nature"); feminacy "female nature" (1829); feminicity "quality or condition of being a woman" (1843). Also feminality (1640s, "quality or state of being female"), from rare adjective feminal "female, belonging to a woman" (late 14c.), from Old French feminal. And femineity "quality or state of being feminine," also "effeminate; womanly," from Latin femineus "of a woman, pertaining to a woman." feminile "feminine" (1640s) seems not to have survived.

ldlate 14c., "decreed by fate," also "fraught with fate," from O French fatal (14c.) and directly from Latin fatalis "ordained by fate, decreed, destined; of or belonging to fate or destiny; destructive, deadly," from fatum (see fate (n.)). Original senses are obsolete; the meaning "causing or attended with death" in English is from early 15c. Meaning "concerned with or dealing with destiny" is from mid-15c.

beautiful enchantress of the isle of Aea who transformed into swine those who drank from her cup ("Odyssey"), late 14c., from Latin Circe, from Greek Kirke. Related: Circean "fascinating but depraving" (1640s).