Fill out means to complete a form, questionnaire or application by writing in all the required information. The second meaning is to become less thin and stronger: people say it about a skinny teenager who has grown broader in the shoulders, or about a face that has become fuller.
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fill out + a form/application/questionnaire; fill it out; fill out (= become less thin)
- I spent twenty minutes filling out the visa application online.
- New students have to fill out a short questionnaire about their level of English.
- My nephew was really skinny at fifteen, but he's filled out since he started swimming.
What changed
First versionPlease fill the application form and bring it to reception.
RevisionPlease fill out the application form and bring it to reception.
It's tempting to use just fill, but without a particle fill means to make something full: fill a glass with water. With documents, you need a particle: fill out the form or fill in the form.
In British English, people more often say fill in for forms, and in American English fill out, but both are understood. However, fill in has a meaning that fill out doesn't: to do someone's work while they're away. Can you fill in for me on Friday? You can't say fill out for me in this sense.
Your turn
Before the doctor sees you, please ___ this form with your address and medical history.
Show the answer
fill out — At the doctor's, you complete a form by writing in your address and medical history, so fill out fits. Fill up means to make something completely full, like a petrol tank or a glass; nobody says it about a form.
Think of a document you filled out recently: a questionnaire, an application or a visa form. Write what the document was and what information you had to give.
Last week I filled out a rental application and had to give my salary, my employer's phone number and two references.
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