(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.