(1):

(a.) First after the fifth; next in order after the fifth.

(2):

(a.) Constituting or being one of six equal parts into which anything is divided.

(3):

(n.) The quotient of a unit divided by six; one of six equal parts which form a whole.

(4):

(n.) The next in order after the fifth.

(5):

(n.) The interval embracing six diatonic degrees of the scale.