(1):

(n.) The quotient of a unit divided by seven; one of seven equal parts into which anything is divided.

(2):

(n.) One next in order after the sixth; one coming after six others.

(3):

(a.) Constituting or being one of seven equal parts into which anything is divided; as, the seventh part.

(4):

(a.) Next in order after the sixth;; coming after six others.

(5):

(n.) An interval embracing seven diatonic degrees of the scale.

(6):

(n.) A chord which includes the interval of a seventh whether major, minor, or diminished.