Definition of thirteenth

• a. - Next in order after the twelfth; the third after the tenth; -- the ordinal of thirteen; as, the thirteenth day of the month.
• a. - Constituting or being one of thirteen equal parts into which anything is divided.
• n. - The quotient of a unit divided by thirteen; one of thirteen equal parts into which anything is divided.
• n. - The next in order after the twelfth.
• n. - The interval comprising an octave and a sixth.