1. The ordinal number matching the number eight in a series.
2. One of eight equal parts.

[Middle English eighthe, from Old English eahtotha, from eahta, eight.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.