con·cave
adjective/kɒnˈkeɪv/
/kɑːnˈkeɪv/
- (of an outline or a surface) curving in
enlarge image凹的；凹面的 - a concave lens/mirror
凹透镜；凹镜 - The upper surface is slightly concave.
上表面稍凹。 - The inside of a shiny spoon is a common example of a concave mirror.
光亮的调羹内层就是一种常见的凹镜。
Oxford Collocations DictionaryConcave is used with these nouns:- mirror
Word Originlate Middle English: from Latin concavus, from con- ‘together’ + cavus ‘hollow’. - a concave lens/mirror