Pronunciation: (twen'tē-wun', twun'-), [key]
1. a cardinal number, 20 plus 1.
2. a symbol for this number, as 21 or XXI.
3. a set of this many persons or things.
4. Also,21.Also called blackjack. a gambling game at cards, in which the object is to obtain from the dealer cards whose values add up to, or close to, 21 but which do not exceed it.
amounting to 21 in number.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.