papilledema (n.)

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.

also oedema, "excessive accumulation of serum in tissue spaces or a body cavity," c. 1400, idema, "a swelling filled with phlegmatic humors," from medical Latin, from Greek oidēma (genitive oidēmatos) "a swelling tumor," from oidein "to swell," from oidos "tumor, swelling," from PIE *oid- "to swell," source also of Latin aemidus "swelling;" Armenian aitumn "a swelling," aytnum "to swell;" Old Norse eista "testicle," Old High German eittar "pus," Old English attor "poison" (that which makes the body swell), and the first element in Oedipus.