# fill sth in

CEFR A2 · Phrasal verb

Source: https://englishreference.com/word/fill-sth-in
Updated: 2026-04-24

## Definition

To write information in the empty spaces on a form or document.

For teachers: To add required information to the blank spaces of a document, form, or questionnaire. This transitive phrasal verb is separable.

## Examples

- Please fill in this form with your details.
- You need to fill in your name and address on the first page of the application.
- The historian had to carefully fill in the gaps in the manuscript, using contextual clues from other contemporary sources.

## Pitfalls

- Not "Please fill the form." but "Please fill in the form." — The particle 'in' is required to form the phrasal verb meaning 'to complete'.

## Usage notes

- Commonly used for forms, applications, and documents that have blank spaces for information.
- Teaching tip: Contrast with 'fill out', a near-synonym in American English; 'fill in' can focus on specific blanks, while 'fill out' often implies completing the entire document.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.