A slide whistle is a wind instrument consisting of a fipple like a recorder's and a tube with a piston in it. Thus it has an air reed like some woodwinds, but varies the pitch with a slide. The construction is rather like a bicycle pump. Because the air column is cylindrical and open at one end and closed at the other, it overblows the third harmonic. "A whistle made out of a long tube with a slide at one end. An ascending and descending glissando is produced by moving the slide back and forth while blowing into the mouthpiece." "Tubular whistle with a plunger unit in its column, approximately 12 inches long. The pitch is changed by moving the slide plunger in and out, producing ascending and descending glisses."

A wind instrument is a musical instrument that contains some type of resonator in which a column of air is set into vibration by the player blowing into a mouthpiece set at or near the end of the resonator. The pitch of the vibration is determined by the length of the tube and by manual modifications of the effective length of the vibrating column of air. In the case of some wind instruments, sound is produced by blowing through a reed; others require buzzing into a metal mouthpiece, while yet others require the player to blow into a hole at an edge, which splits the air column and creates the sound.