What is the origin of fecund?
The English adjective fecund ultimately comes from Latin fēcundus “fertile, productive,” used of humans, animals, and plants. The first syllable fē– is a Latin development of the Proto-Indo-European root dhē(i)– “to suck, suckle.” From fē– Latin forms the derivatives fēlīx “fruitful, productive, fortunate, blessed, lucky” (source of the English name Felix and felicity), fēmina “woman” (originally a feminine participle meaning “suckling”), fētus “parturition, birth, conception, begetting, young (plant or animal), child,” and fīlius and fīlia “son” and “daughter,” respectively (and source of filial). Dhē(i)– appears in Greek as thē(i)-, as in thêsthai “to suckle” and thēlḗ “nipple, teat” (an element of the uncommon English noun thelitis “inflammation of the nipple”). Fecund entered English in the 15th century.