(1):

(a.) Of or pertaining to the interval of the octave and the fourth.

(2):

(a.) Next after the tenth; as, the eleventh chapter.

(3):

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

(4):

(a.) Constituting one of eleven parts into which a thing is divided; as, the eleventh part of a thing.

(5):

(n.) The interval consisting of ten conjunct degrees; the interval made up of an octave and a fourth.