# convex

/ˈkɑnˌvɛks/ (US) · /kɒnvˈɛks/ (UK) · CEFR C1 · Adjective

Source: https://englishreference.com/word/convex
Updated: 2026-05-07

## Definition

curved outward like the surface of a ball or the back of a spoon. You use this to describe shapes that bulge toward you.

For teachers: having a surface that curves outward rather than inward. Often contrasted with 'concave' in geometry and optics.

## Examples

- The back of a spoon has a convex shape.
- Security mirrors in shops are usually convex to provide a wider field of vision for the staff.
- The architect designed the building with a massive convex glass wall that reflects the surrounding skyline in a distorted, panoramic arc.

## Pitfalls

- Not "a convex mirror curves inward" but "a convex mirror curves outward" — Learners frequently confuse 'convex' (curving out) with 'concave' (curving in like a cave).

## Usage notes

- Typically used to describe physical surfaces, lenses, or mathematical curves.

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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.