Pronunciation: (thûr'tē-fûrst'), [key]
1. next after the thirtieth; being the ordinal number for 31.
2. being one of 31 equal parts.
1. a thirty-first part, esp. of one (1/31).
2. the thirty-first member of a series.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.