1.
If you fill out a form or other document requesting information, you write information in the spaces on it. ( mainly AM; in BRIT, usually use fill in )
Fill out the application carefully, and keep copies of it.
= fill in
PHRASAL VERB : V P n (not pron) , also V n P
2.
If a fairly thin person fills out , they become fatter.
A girl may fill out before she reaches her full height.
PHRASAL VERB : V P