Noun.  Under the Whyte notation system, a simple form of steam locomotive, with three axles connecting six driving wheels, and no leading wheels or trailing wheels.

This is an unmodified, but possibly outdated, definition from Wiktionary and used here under the Creative Commons license. Wiktionary is a great resource. If you like it too, please donate to Wikimedia.

This entry was last updated on RefTopia from its source on 3/20/2012.