(1):

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

(2):

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

(3):

(n.) The interval comprising an octave and a sixth.

(4):

(a.) Next in order after the twelfth; the third after the tenth; - the ordinal of thirteen; as, the thirteenth day of the month.

(5):

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