One who denounces, discloses, or betrays; an accuser or betrayer.

An informer.

A person who or (occasionally) thing which makes known, discloses, or reveals a secret; an informer. Obsolete.

One who denounces or utters denunciations; a denouncer; in Civ. Law: One who lays an information against another.

A person who informs against another. Originally (more fully common informer): a person who lays an information (information, n. 5a) against an…

One who denounces, in various senses of the verb. One who informs against, accuses, delates.

A person or thing that discloses, brings to light, or reveals; one who informs against or accuses; a revealer; an informer, an accuser. Obsolete.

An informer, a secret or professional accuser.

Ancient Greek History. One of a class of informers in ancient Athens: see quots. and etymology above.

A detective, informer, or spy. Obsolete.

One who keeps watch upon the actions of another; a watchman. †Formerly often in opprobrious sense: A mean spy, a ‘sneak’: cf. scout, n.2 Also spec.…

†(a) (perhaps) a recipient or object of something (obsolete); (b) (originally and chiefly U.S.) a member of a criminal gang who provides…

An informer, a spy.

Roman History. An informer; a person paid to denounce another in a court. Now rare.

spec. = informer, n. 2.

Apparently: an informer or promoter (promoter, n. 3).

A person employed to gather or provide information; an informer. Cf. outrunner, n.1 1.

slang. An informer; esp. in phrase to turn stag. Also see quot. 1725.

An informer; one who turns King's or Queen's evidence. In the phrase to turn snitch.

Designating, relating to, or characterized by this type of action.

Cant. (See quot. 1795) Obsolete.

slang. An informer; a detective; a policeman.

Jamieson has ‘An ugly, ill-shaped fellow’. Now gen. Scottish in sense ‘a telltale’.

slang. A college servant who is inclined to pass on information to someone in authority; a telltale. Obsolete. rare.

An informer, peacher; = snitch, n. 3.

a valet, a pageboy; (later also) a contemptible or unpleasant person.

slang (chiefly U.S.). A police informer; = stool-pigeon n. at stool, n. compounds 2.

A person who keeps records, esp. in a book; a bookkeeper. Now rare.

slang. An informer.

Chiefly U.S. slang (derogatory). An informer. Now rare.

British slang. A person who rounds on others; an informer. Obsolete.

colloquial. A tell-tale, an informer.

Criminals' slang. An informer.

Originally and chiefly Criminals' slang (chiefly North American). A (uniformed) police officer; (also) a prison officer. Now rare.

An informer. Australian slang.

slang. An informer, a tale-teller; a complainer.

Criminals' slang. An informer. Cf. squealer, n. 2b.

slang (chiefly U.S.). A person who gives information, esp. of an incriminating nature, to the police or other authority; an informer. Cf. to sing (a…

slang. An informer. rare.

= nark, n. 2.

(a) In schools: an informer, a tell-tale. (b) One who curries favour, a toady; generally, an obnoxious person.

U.S. slang. An informer. Cf. rat, n.1 4e.

An informer. Cf. sing, v.1 4d. Criminals' slang.

A person supplying information, esp. in connection with criminal activity. slang.

An informer. Also top-off merchant (merchant, adj. 1).

A spy; an informer. Cf. tout, v.1 2. Irish English (northern) and Scottish.

An obnoxious or contemptible person; spec. an informer, a traitor.

one who ‘blows the whistle’ on a person or activity (see sense 1b(d)), esp. from within an organization.