1
general::
Phrase(s): fill out
to become full; to gain weight. • About a month after her debilitating illness, Maggie began to fill out again. • The fruit on the trees began to fill out, and we knew it was going to ripen soon., Phrase(s): fill something out
Fig. to complete a form by writing in the blank spaces. • Please fill this form out and send it back to us in the mail. • I will fill out the form as you asked.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Complete by supplying required information, especially in writing. For example, Please fill out the application form, or I don't quite understand this drawing, so fill out the details. [Late 1800s] 2. Become enlarged, distended, rounded in outline. For example, The wind filled out the sails, or He's put on weight and really filled out. Applied to objects, this expression dates from about 1700, but to persons or animals becoming fatter, only from the late 1800s.
American Heritage Idioms