sérpents
“snake, serpent, creeping thing”snake
From *serp- "to creep". Gives Latin serpēns, Sanskrit sárpa, Greek hérpein.
Discussion
The reconstructed noun *sérpents ("snake, serpent, creeping thing") derives from the verbal root *serp- ("to creep, to crawl"), treated in Pokorny (IEW 912–913). The formation is a present participle: *sérp-ont-s, literally "the creeping one," a transparent description that was lexicalized as the standard word for snake in several branches.
Latin serpēns, serpentis ("snake, serpent") directly continues the participial formation and is the source of English serpent, serpentine, and the heraldic and astronomical uses of the term. The verb serpere ("to creep, to crawl") preserved the base verb.
Greek hérpō (ἕρπω, "I creep, I crawl") shows the expected *s > h in initial position. The derivative herpetón (ἑρπετόν, "creeping thing, reptile") gives English herpetology (the study of reptiles) and herpes (a "creeping" skin disease, so named by Galen for its spreading character).
Sanskrit sárpati ("creeps, crawls") and sarpá- ("snake, serpent") preserve both the verb and the nominal derivative. The mythological Nāga serpents of Indian tradition, while using a different lexeme, exist in a cultural context where serpent vocabulary is deeply embedded.
In Slavic, Old Church Slavonic is not directly attested for this root, but Albanian gjarpër ("snake") is a cognate with characteristic Albanian phonological developments.
The participial formation *sérp-ont-s is typologically significant: naming an animal by its characteristic action ("the creeper") is a common PIE strategy, paralleled by *h₂ŕ̥tḱos ("bear," literally "the destroyer") and other taboo-replacement names. Whether "serpent" itself was a euphemistic replacement for an older, tabooed snake-word is plausible but unproven.
Notes
Also source of "herpes" (creeping skin condition)