Pronunciation: (ā'tēnth'), [key]
1. next after the seventeenth; being the ordinal number for 18.
2. being one of 18 equal parts.
1. an eighteenth part, esp. of one (1/18).
2. the eighteenth member of a series.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.