A triplet is 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 Tandem bicycle with three seats Photography triplet or paint triplet The Triplets may refer to: The Triplets, a Catalan children's book The Triplets (band), a Latin pop group Troy Aikman, Emmitt Smith, and Michael Irvin of NFL fa… (More on Triplet)