# flap

/ˈfɫæp/ (US) · /flˈæp/ (UK) · CEFR B1 · Noun

Source: https://englishreference.com/word/flap
Updated: 2026-05-06

## Definition

a flat piece of something that is attached on one side and can move up and down or back and forth. You often see these on pockets, boxes, or even on the wings of an airplane.

For teachers: a flat, flexible piece of material attached at one edge, allowing it to hang loose or cover an opening. Often refers to mechanical surfaces on aircraft wings used to control lift.

## Examples

- He closed the flap of the envelope before mailing it.
- The pilot adjusted the wing flaps to increase lift during the final approach to the runway.
- A loose flap of canvas on the tent rattled incessantly against the poles as the wind picked up during the night.

## Usage notes

- Commonly used to describe parts of clothing, packaging, or anatomical structures in medical contexts.

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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.