# concave

/ˈkɑnkeɪv/ (US) · /kɒnkˈeɪv/ (UK) · CEFR B2 · Adjective

Source: https://englishreference.com/word/concave
Updated: 2026-05-11

## Definition

curving inward like the inside of a bowl or a spoon. It is the opposite of convex, which curves outward.

For teachers: curving or hollowing inward; having a surface that is lower in the middle than at the edges. Often used in optics to describe lenses that diverge light.

## Examples

- The inside of a spoon has a concave shape.
- The architect designed a concave wall to help focus the sound toward the center of the auditorium.
- A concave lens causes parallel rays of light to spread out, making it an essential component in corrective eyewear for people with nearsightedness.

## Pitfalls

- Not "a concave mirror curves outward" but "a concave mirror curves inward" — Learners frequently confuse 'concave' with 'convex'; remember that 'cave' implies a hollow space going inward.

## Usage notes

- Typically used attributively before a noun or predicatively after a linking verb like 'is' or 'appears'.

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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.