1. The act of riding.
2. Horseback riding.

1. An administrative division or electoral division in Canada.
2. Any one of three former administrative divisions of Yorkshire, England.

[Middle English, alteration of trithing, from Old English *thrithing, from Old Norse thridhjungr, third part, from thridhi, third.]

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.