Triplet

Triplet is a term used in various fields to denote a group of three related items. In mathematics and related disciplines, a triplet or 3-tuple refers to an ordered collection of three elements, typically denoted (a, b, c).

In mathematics, triplets are used to represent coordinates, components of vectors, or elements of a Cartesian product. Some contexts use unordered sets of three items, but the standard 'triplet' implies order.

In music, a triplet is a rhythm where three notes occupy the time normally given to two notes of the same value. Notated with a bracket and the number 3, triplets create a dividing ratio of three to two in the beat.

In genetics and molecular biology, a codon is a triplet of nucleotides in DNA or RNA that specifies an amino acid or a stop signal. The genetic code uses triplets; reading frames depend on starting positions. Triplet repeats are sequences of three nucleotides that can expand and cause disorders.

In physics, a triplet state refers to a state with two unpaired electrons with parallel spins; common in diatomic oxygen (O2).

In machine learning, a triplet forms part of a triplet loss framework: an anchor, a positive example, and a negative example used to learn embeddings.

In everyday use, triplets refer to three offspring born in a single birth.