v.1. To provide required information in written form on something, such as a document: She carefully filled out the job application. He filled the voter registration form out.
2. To become larger, fuller, or fatter: The child filled out after he reached puberty.
3. To cause something to become larger, fuller, or fatter: The reporter filled out the article with extra anecdotes. The speaker filled the lecture out with a slide show.
4. To be large enough to fit some article of clothing properly: You don't really fill out that dress—it is a little baggy in places.