(1):
(n.) The next in order after the nineteen; one coming after nineteen others.
(2):
(n.) The quotient of a unit divided by twenty; one of twenty equal parts of one whole.
(3):
(a.) Consisting, or being, one of twenty equal parts into which anything is divided.
(4):
(a.) Next in order after the nineteenth; tenth after the tenth; coming after nineteen others; - the ordinal of twenty.