3. One of three; third. Triple crown, the crown, or tiara, of the pope. See Tiara. Triple-expansion steam engine, a compound steam engine in which the same steam performs work in three cylinders successively. Triple measure, a measure of tree beats of which first only is accented.
(Science: mathematics) Triple ratio, that time in which each measure is divided into three equal parts. Triple valve, in an automatic air brake for railroad cars, the valve under each car, by means of which the brake is controlled by a change of pressure in the air pipe leading from the locomotive.
Origin: L. Triplus; tri- (see Tri-) _ -plus, as in duplus double: cf. F. Triple. See Double, and cf. Treble.