Толковый словарь английского языка - triplet

noun Etymology: 2triple Date: 1656 a unit of three lines of verse, 2. a combination, set, or group of three, a group of three elementary particles (as positive, negative, and neutral pions) with different charge states but otherwise similar properties, an atom or molecule with an even number of electrons that have a net magnetic moment, codon, one of three children or offspring born at one birth, a group of three musical notes or tones performed in the time of two of the same value