The undertail coverts together with the feathers in the vent region; sometimes contrastingly coloured, like in the D'Arnaud's Barbet <ref name="Kenya">Zimmerman, Dale A.; et al. (1999). Birds of Kenya and Northern Tanzania. Princeton University Press. p. 432. ISBN0691010226.</noinclude>. As an adjective, it is called crissal, the Crissal Thrasher is the only bird with this word in its name.
This article is part of Project Glossary, a All Birds project that aims to write comprehensive articles on each term related to animals.