"of, on, or in the back of the head," 1540s, from French occipital, from Medieval Latin occipitalis, from Latin occiput (genitive occipitis) "back of the skull," from assimilated form of ob "in the way of, against," here with a sense of "in back of" (see ob-) + caput "head" (from PIE root *kaput- "head"). As a noun, "the occipital bone," from 1758. Middle English had occiput (n.) "back of the head" and occipiciale (n.) "occipital bone."
1640s, "a swelling tumor on the body; anything swelled or pushed beyond the surrounding or adjacent surface," from Late Latin protuberantem (nominative protuberans), present participle of protuberare "to swell, bulge, grow forth," from Latin pro "forward" (see pro-) + tuber "lump, swelling" (from PIE root *teue- "to swell"). Meaning "fact or condition of swelling or pushing beyond the surrounding or adjacent surface" is by 1680s. Related: Protuberancy.
"knob, lump, bump, protuberance," 1590s, variant of dialectal knub, which is probably a variant of knob. Figurative meaning "point, gist" is attested by 1834.
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.