1. Write all the required information onto a form
   "fill out this questionnaire, please!";
   - complete, fill in, make out
    
2. Become round, plump, or shapely
   "The young woman is filling out";
   - round, flesh out
    
3. Make fat or plump
   "The farmer filled out the pigs for market";
   - fatten, fat [archaic], flesh out, plump, plump out, fatten out, fatten up
    
4. Make bigger, better or more complete
   "Adding a conclusion will fill out your essay nicely";
   - round out
    
5. Supplement what is thought to be deficient
   "He filled out his meagre pay by giving private lessons";
   - eke out
    
6. Line or stuff with soft material
   "fill out a bra";
   - pad

Derived forms: filled out, filling out, fills out

Type of: alter, change, enrich, gain, modify, put on, stuff, supplement, write