triplet

Short definition from Wiktionary

Noun

1. 1
   A set of three, particularly: A group of three notes played or written where two notes would ordinarily be; a form of tuplet.
2. 2
   A set of three, particularly: A triquark.
3. 3
   A set of three, particularly: A quantum state with three allowed projections for the spin.
4. 4
   A set of three, particularly: A constructed gem consisting of a thin slice of natural opal sandwiched between a clear glass or quartz top and a synthetic or stone backing that enhances the colour of the opal.
5. 5
   One of a group of three, particularly
6. 6
   One of a group of three, particularly: One of a group of three siblings born at the same time to the same mother.

Proper noun

1. 1
   A surname.