gag (v.) Look up gag at
mid-15c., transitive, "to choke, strangle," possibly imitative and perhaps influenced by Old Norse gaghals "with head thrown back." The sense of "stop a person's mouth" is first attested c.1500. Related: Gagged; gagging.
gag (n.2) Look up gag at
"joke," 1863, probably related to theatrical sense of "matter interpolated in a written piece by the actor" (1847); or from the sense "made-up story" (1805); or from slang verbal sense of "to deceive, take in with talk" (1777), all perhaps on notion of "stuff, fill" (see gag (v.)).
gag (n.1) Look up gag at
"act of gagging," 1550s, from gag (v.); figurative use from 1620s.