"very venomous snake of Egypt," 1520s, earlier aspis (mid-14c.), from Old French aspe "asp" (13c.) or directly from Latin aspidem (nominative aspis), from Greek aspis "an asp, Egyptian viper," literally "a round shield;" the serpent so called probably in reference to its neck hood. As to the etymology of the Greek word, Beekes finds that "No remotely convincing suggestions have been made." The name was subsequently applied to the common vipers and adders of Europe, which however are only slightly venomous.
updated on June 29, 2018