WordWeb Online

1. Make fat or plump
   - fatten, fat, fill out, plump, plump out, fatten out, fatten up
    
2. Add details, as to an account or idea; clarify the meaning of and discourse in a learned way, usually in writing
   - elaborate, lucubrate [archaic], expatiate, exposit, enlarge, expand, expound, dilate
    
3. Become round, plump, or shapely
   "The young woman is fleshing out";
   - round, fill out

Derived forms: fleshes out, fleshed out, fleshing out

Type of: alter, change, clarify, clear up, elucidate, gain, modify, put on