WordWeb Online

1. State
   "exposit one's reasons";
   - set forth, expound
    
2. Add details, as to an account or idea; clarify the meaning of and discourse in a learned way, usually in writing
   "She exposited on the main ideas in her dissertation";
   - elaborate, lucubrate [archaic], expatiate, enlarge, flesh out, expand, expound, dilate

Derived forms: exposits, exposited, expositing

Type of: clarify, clear up, elucidate