Webster's Revised Unabridged Dictionary · 1913

Gag

Gag , transitive verb

[Probably from Welsh cegio to choke or strangle, from ceg mouth, opening, entrance.]

1.
To stop the mouth of, by thrusting sometimes in, so as to hinder speaking; hence, to silence by authority or by violence; not to allow freedom of speech to. — Marvell
The time was not yet come when eloquence was to be gagged, and reason to be hood winked. — Maccaulay
2.
To pry or hold open by means of a gag.
Mouths gagged to such a wideness. — Fortescue (Transl.)
3.
To cause to heave with nausea.

Gag , intransitive verb

1.
To heave with nausea; to retch.
2.
To introduce gags or interpolations. See Gag, n., 3. [Slang] — Cornill Mag

Gag , noun

1.
Something thrust into the mouth or throat to hinder speaking.
2.
A mouthful that makes one retch; a choking bit; as, a gag of mutton fat. — Lamb
3.
A speech or phrase interpolated offhand by an actor on the stage in his part as written, usually consisting of some seasonable or local allusion. [Slang]
Collocations (2)
Gag rein (Harness) , a rein for drawing the bit upward in the horse's mouth.
Gag runner (Harness) , a loop on the throat latch guiding the gag rein.