It appears (http://www.google.com/search?hl=en&ie=ISO-8859-1&q=%22deponent+verb%22) to be a latin concept.

... (http://www.arts.cuhk.edu.hk/Lexis/Wheelock-Latin/lat34.txt) a deponent verb is a verb which is passive in form but passive in meaning.

Active in meaning, surely?!

(You appear to have unfortunately copied from the one link returned by Google which made that typo. Several others on the front page get it right...)