A group of four people or things, particularly
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 seven things.
A period of seven years.
The seven notes of the diatonic scale.
Of seventh rank or order.
Consisting of or containing seven.
Lasting seven years; continuing seven years.