1630s, "one who stares open-mouthed in wonder," agent noun from gape (v.). Gaper delay in traffic control parlance attested by 1995.
early 13c., from an unrecorded Old English word or else from Old Norse gapa "to open the mouth wide, gape" (see gap (n.)). Related: Gaped; gaping. As a noun, "act of opening the mouth," from 1530s.
updated on February 11, 2015