septenary

Consisting of or containing seven.

Of seventh rank or order.

... indeed if further evidence than that of bestial and savage counting were required to show that finger-numeration and the quinary system were not primeval, it would be afforded by the development of the senary-septenary system in so many lands.

Lasting seven years; continuing seven years.

Septenary penance.

A group of seven things.

A period of seven years.

This idea was based on the doctrine that a man's body changed its character every seven years and that his life was thus made up of ‘septenaries’.

The seven notes of the diatonic scale.