<p><strong>Verb</strong></p><ul><li>(used without object) to make a clear musical sound, a series of such sounds, or a high-pitched, warbling sound by the forcible expulsion of the breath through a small opening formed by contracting the lips, or through the teeth, with the aid of the tongue.</li><li>to make such a sound or series of sounds otherwise, as by blowing on some device.</li><li>to emit similar sounds from the mouth, as birds do.</li><li>(of a device) to produce a similar sound when actuated by steam or the like: This teakettle whistles when it boils.</li><li>to move, go, pass, etc., with a whistling or whizzing sound, as a bullet or the wind.</li></ul><p><strong>Noun</strong></p><ul><li>an instrument for producing whistling sounds by means of the breath, steam, etc., as a small wooden or tin tube, a pipe, or a similar device with an air chamber containing a small ball that oscillates when air is forced through an opening, producing a high-pitched, warbling tone.</li><li>a sound produced by whistling: a prolonged whistle of astonishment.</li><li>a simple fipple flute.</li></ul><p><strong>Verb Phrase</strong></p><ul><li>to demand or expect without success: After promising to pay, he told us we could whistle for our money.</li></ul>