feminity n.

*dhē(i)-, Proto-Indo-European root meaning "to suck."

It forms all or part of: affiliate; affiliation; effeminate; effete; epithelium; fawn (n.) "young deer;" fecund; fellatio; Felicia; felicitate; felicity; Felix; female; feminine; femme; fennel; fenugreek; fetal; feticide; fetus; filial; filiation; filicide; filioque; fitz; infelicity.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit dhayati "sucks," dhayah "nourishing;" Greek thēlē "mother's breast, nipple," thēlys "female, fruitful;" Latin felare "to suck," femina "woman" ("she who suckles"), felix "happy, auspicious, fruitful," fetus "offspring, pregnancy;" fecundus "fruitful, fertile, productive; rich, abundant;" Old Church Slavonic dojiti "to suckle," dojilica "nurse," deti "child;" Lithuanian dėlė "leech;" Old Prussian dadan "milk;" Gothic daddjan "to suckle;" Old Swedish dia "suckle;" Old High German tila "female breast;" Old Irish denaim "I suck," dinu "lamb."

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.