Bridle
Three Hebrew words are thus rendered in the Authorized Version. (1.) Heb. mahsom’ signifies a muzzle or halter or bridle, by which the rider governs his horse (Ps 39:1).
(2.) Me’theg, rendered also “bit” in Ps 32:9, which is its proper meaning. Found in 2 Kgs 19:28, where the restraints of God’s providence are metaphorically styled his “bridle” and “hook.” God’s placing a “bridle in the jaws of the people” (Isa 30:28; Isa 37:29) signifies his preventing the Assyrians from carrying out their purpose against Jerusalem.
(3.) Another word, re’sen, was employed to represent a halter or bridle-rein, as used Ps 32:9; Isa 30:28. In Job 30:11 the restraints of law and humanity are called a bridle.
From Easton’s Bible Dictionary (1897), by Matthew George Easton.