twen•ty-firstPronunciation: (twen'tē-fûrst', twun'-), [key]
next after the twentieth; being the ordinal number for 21.
being one of 21 equal parts.
a twenty-first part, esp. of one (1/21
the twenty-first member of a series.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.