A triplet's a set of three items. It may refer to: one of three babies in a multiple birth Opal in preparation to be a gemstone Tuple of length 3 in mathematics Tuplet in music Tercet in poetry Spin triplet in quantum mechanics — as in triplet oxygen, or simply triplet state in general. Tandem bicycle with three seats Photography triplet or paint triplet J-coupling as part of NMR spectroscopy A series of three nucleotide bases that form Genetic code The Triplets may refer to: T… (More on Triplet)