Definition of: guard

(gärd) v.t.
1. To stand guard over (a door, pass, etc.).
2. To watch over so as to keep from harm, loss, etc.; protect.
3. To watch over so as to keep from escaping.
4. To keep a check on; restrain: Guard your tongue.
5. Archaic To escort.
—v.i.
6. To take precautions; be on guard. See synonyms under KEEP, PRESERVE, SHELTER.
—noun
1. One who or that which protects, defends, or secures from loss, injury, or attack; hence, defense; protection; watch.
2. Specifically, a man or a body of men occupied in preserving a person or place from attack, or in controlling prisoners or preventing their escape.
3. Precaution against surprise or attack; care; attention.
4. A posture, attitude, or condition of defense.
5. Any of various protective or defensive devices for wearing, or for attaching to an object, as a machine or implement.
6. Brit. A railway official in charge of a train; a conductor.
7. U.S. An official employed on elevated and subway trains at points of entrance and egress.
8. In football, one of two line players (the right guard and left guard) who support the center; also, one of two players in basketball with similar positions and titles. See synonyms under DEFENSE, RAMPART.
—on guard
1. Ready for defense or protection; on the watch, as a military guard.
2. The first position in fencing or in bayonet exercises. Also, French, en garde. [<OF guarder, garder <Gmc. Akin to WARD.]
—guard′er noun