An arrangement of three objects arranged one behind the other.
A group of three notes played or written where two notes would ordinarily be; a form of tuplet.
One of a group of three, particularly
One of a group of three siblings born at the same time to the same mother.
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.
A quantum state with three allowed projections for the spin.
A triquark.