Old English gielpan (West Saxon), gelpan (Anglian) "to boast, exult," from Proto-Germanic *gel- (source also of Old Saxon galpon, Old Norse gjalpa "to yelp," Old Norse gjalp "boasting," Old High German gelph "outcry"), from PIE root *ghel- (1) "to call, cry out." Meaning "utter a quick, sharp, bark or cry" is 1550s, probably from the noun. Related: Yelped; yelping.
Old English gielp "boasting, pride, arrogance," from source of yelp (v.). Meaning "quick, sharp bark or cry" is attested from early 16c.