triplet

Etymology

PIE word *tréyes From triple + -et, q.v.

noun

1. A set of three, particularly
   1. (music) A group of three notes played or written where two notes would ordinarily be; a form of tuplet.
   2. (physics) A triquark.
   3. (physics) A quantum state with three allowed projections for the spin.
   4. 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.
2. One of a group of three, particularly
   1. One of a group of three siblings born at the same time to the same mother.