Pronunciation: (thûr'tēnth'), [key]
1. next after the twelfth; being the ordinal number for 13.
2. being one of 13 equal parts.
1. a thirteenth part, esp. of one (1/13).
2. the thirteenth member of a series.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.