'Guard duty' definitions:

Definition of 'guard duty'

From: WordNet

noun

The duty of serving as a sentry; "he was on guard that night" [syn: guard duty, guard, sentry duty, sentry go]

Definition of 'Guard duty'

From: GCIDE

Guard \Guard\, n. [OF. guarde, F. garde; of German origin; cf. OHG. wart, warto, one who watches, warta a watching, Goth. wardja watchman. See Guard, v. t.] [1913 Webster]
1. One who, or that which, guards from injury, danger, exposure, or attack; defense; protection. [1913 Webster]
His greatness was no guard to bar heaven's shaft. --Shak. [1913 Webster]
2. A man, or body of men, stationed to protect or control a person or position; a watch; a sentinel. [1913 Webster]
The guard which kept the door of the king's house. --Kings xiv. 27. [1913 Webster]
3. One who has charge of a mail coach or a railway train; a conductor. [Eng.] [1913 Webster]
4. Any fixture or attachment designed to protect or secure against injury, soiling, or defacement, theft or loss; as: (a) That part of a sword hilt which protects the hand. (b) Ornamental lace or hem protecting the edge of a garment. (c) A chain or cord for fastening a watch to one's person or dress. (d) A fence or rail to prevent falling from the deck of a vessel. (e) An extension of the deck of a vessel beyond the hull; esp., in side-wheel steam vessels, the framework of strong timbers, which curves out on each side beyond the paddle wheel, and protects it and the shaft against collision. (f) A plate of metal, beneath the stock, or the lock frame, of a gun or pistol, having a loop, called a bow, to protect the trigger. (g) (Bookbinding) An interleaved strip at the back, as in a scrap book, to guard against its breaking when filled. [1913 Webster]
5. A posture of defense in fencing, and in bayonet and saber exercise. [1913 Webster]
6. An expression or admission intended to secure against objections or censure. [1913 Webster]
They have expressed themselves with as few guards and restrictions as I. --Atterbury. [1913 Webster]
7. Watch; heed; care; attention; as, to keep guard. [1913 Webster]
8. (Zool.) The fibrous sheath which covers the phragmacone of the Belemnites. [1913 Webster]
Note: Guard is often used adjectively or in combination; as, guard boat or guardboat; guardroom or guard room; guard duty. [1913 Webster]
Advanced guard, Coast guard, etc. See under Advanced, Coast, etc.
Grand guard (Mil.), one of the posts of the second line belonging to a system of advance posts of an army. --Mahan.
Guard boat. (a) A boat appointed to row the rounds among ships of war in a harbor, to see that their officers keep a good lookout. (b) A boat used by harbor authorities to enforce the observance of quarantine regulations.
Guard cells (Bot.), the bordering cells of stomates; they are crescent-shaped and contain chlorophyll.
Guard chamber, a guardroom.
Guard detail (Mil.), men from a company regiment etc., detailed for guard duty.
Guard duty (Mil.), the duty of watching patrolling, etc., performed by a sentinel or sentinels.
Guard lock (Engin.), a tide lock at the mouth of a dock or basin.
Guard of honor (Mil.), a guard appointed to receive or to accompany eminent persons.
Guard rail (Railroads), a rail placed on the inside of a main rail, on bridges, at switches, etc., as a safeguard against derailment.
Guard ship, a war vessel appointed to superintend the marine affairs in a harbor, and also, in the English service, to receive seamen till they can be distributed among their respective ships.
Life guard (Mil.), a body of select troops attending the person of a prince or high officer.
Off one's guard, in a careless state; inattentive; unsuspicious of danger.
On guard, serving in the capacity of a guard; doing duty as a guard or sentinel; watching.
On one's guard, in a watchful state; alert; vigilant.
To mount guard (Mil.), to go on duty as a guard or sentinel.
To run the guard, to pass the watch or sentinel without leave.
Syn: Defense; shield; protection; safeguard; convoy; escort; care; attention; watch; heed. [1913 Webster]