plural papillae, 1690s, "a nipple of a mammary gland," from Latin papilla "nipple," diminutive of papula "swelling" (see pap (n.2)). Meaning "nipple-like protuberance" attested from 1713.
Entries linking to papilla
pap n.2
"nipple of a woman's breast," late 12c., pappe, first attested in Northern and Midlands writing, probably from a Scandinavian source (not recorded in Old Norse, but compare dialectal Swedish pappe), from PIE imitative root *pap- "to swell" (source also of Latin papilla "nipple," which might rather be the source of the English word, papula "a swelling, pimple;" Lithuanian papas "nipple"). Like pap (n.1) supposed to be ultimately of infantile origin.
papillary adj.
"of, pertaining to, or resembling a nipple," 1660s, from Latin papilla "nipple" (see papilla) + -ary.
pap (n.2)papillary (adj.)papilledema (n.)papilloma (n.)