whistle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To produce a clear musical sound by forcing air through the teeth or through an aperture formed by pursing the lips.
• intransitive verb To produce a clear, shrill, sharp musical sound by passing air over or through an opening.
• intransitive verb To produce a high-pitched sound when moving swiftly through the air.
• intransitive verb To produce a high-pitched sound by the rapid movement of air through an opening or past an obstruction.
• intransitive verb To emit a shrill, sharp, high-pitched cry, as some birds and other animals.
• intransitive verb To produce by whistling.
• intransitive verb To summon, signal, or direct by whistling.
• intransitive verb Sports To signal a rule infraction committed by (a player).
• noun A small wind instrument for making whistling sounds by means of the breath.
• noun A device for making whistling sounds by means of forced air or steam.
• noun A sound produced by a whistling device or by whistling through the lips.
• noun A whistling sound, as of an animal or projectile.
• idiom (blow the whistle) To expose a wrongdoing in the hope of bringing it to a halt.
• idiom (whistle in the dark) To attempt to keep one's courage up.

from The Century Dictionary.

• To utter a kind of musical sound by forcing the breath through a small orifice formed by contracting the lips.
• To emit a warbling or sharp, chirping sound or song, as a bird.
• To sound shrill or sharp; move or rush with shrill or whizzing sound.
• To sound a whistle or similar wind- or steam-instrument: as, locomotives whistle at crossings.
• To give information by whistling; hence, to become informer.
• An Australian bird, Colluricincla (or Collurocincla or Collyriocincla) harmonica, the harmonic thrush of Latham, usually placed in the family Laniidæ, now in the Prionopidœ, or another of this genus, as the Tasmanian C. rectirostris (C. selbyi). The species named are 9½ to 10 inches long, chiefly of a gray color varied with brown and white.
• Same as whistlewing.
• Same as whistling coot.
• See snipe 1 .
• In the United States, the common American swan, Cygnus amcricanus or columbianus, as distinguished from the trumpeter, C. (Olor) buccinator.
• To form, utter, or modulate by whistling: as, to whistle a tune or air.
• To call, direct, or signal bv or as by a whistle.
• To send with a whistling sound.
• noun A more or less piercing or sharp sound produced by forcing the breath through a small orifice formed by contracting the lips: as, the merry whistle of a boy.
• noun Any similar sound. Especially— The shrill note of a bird.
• noun A sound made by the wind blowing through branches of trees, the rigging of a vessel, etc., or by a flying missile.
• noun A call or signal made by whistling.
• noun An instrument or apparatus for producing a whistling sound. Whistles are of various shapes and sizes, but they all utilize the principle of the direct flute or flageolet—that of a stream of air so directed through a tube as to impinge on a sharp edge.
• noun Specifically
• noun The small pipe used in signaling, etc., by boatswains, huntsmen, policemen, etc.
• noun A small tin or wooden tube, fitted with a mouthpiece and pierced generally with six holes, used as a musical toy. Often called a penny whistle. See flageolet.
• noun An instrument sounded by escaping steam, used for giving signals, alarms, etc., on railway-engines, steamships, etc. Sec cuts under steam-whistle and passenger-engine.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb To make a kind of musical sound, or series of sounds, by forcing the breath through a small orifice formed by contracting the lips; also, to emit a similar sound, or series of notes, from the mouth or beak, as birds.
• intransitive verb To make a shrill sound with a wind or steam instrument, somewhat like that made with the lips; to blow a sharp, shrill tone.
• intransitive verb To sound shrill, or like a pipe; to make a sharp, shrill sound.
• transitive verb To form, utter, or modulate by whistling.
• transitive verb To send, signal, or call by a whistle.
• transitive verb Hence, in general, to turn loose; to abandon; to dismiss.
• noun A sharp, shrill, more or less musical sound, made by forcing the breath through a small orifice of the lips, or through or instrument which gives a similar sound; the sound used by a sportsman in calling his dogs; the shrill note of a bird.
• noun The shrill sound made by wind passing among trees or through crevices, or that made by bullet, or the like, passing rapidly through the air; the shrill noise (much used as a signal, etc.) made by steam or gas escaping through a small orifice, or impinging against the edge of a metallic bell or cup.
• noun An instrument in which gas or steam forced into a cavity, or against a thin edge, produces a sound more or less like that made by one who whistles through the compressed lips.
• noun colloq. The mouth and throat; -- so called as being the organs of whistling.
• noun (Zoöl.) the American golden-eye.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A device designed to be placed in the mouth in order to make a whistling sound.