A group of four musicians who perform classical music together.
A group of four singers, usually males, who sings together in four-part harmony.
A musical composition in four parts, each performed by a single voice or instrument.
A group of four people or things, particularly
A quaternary compound.
The Quaternary period or the system of deposits laid down during it.
Relating to or in number base four
Of fourth rank or order
Of a mathematical expression containing e.g. x⁴
quaternary ammonium
composed of four elements