A compound crystal, consisting of three individuals.

Intergrowth of three orthorhombic crystals that twin at the center and form a hexagonal shaped crystal.

Cyclic crystal twin that is made up of three crystals.

The repeated playing of two notes in rapid succession. This technique can be used as a substitute for sustaining a note in those instruments, such as the piano, which cannot naturally sustain.

United States literary critic (1905-1975)

One of tree children born at the same birth.