(1):

(a.) Consisting, or being one of, twelve equal parts into which anything is divided.

(2):

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

(3):

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

(4):

(a.) Next in order after the eleventh; coming after eleven others; - the ordinal of twelve.

(5):

(n.) An interval comprising an octave and a fifth.