concave

Definitions

con- (intensive) + cav (hollow) = curved inward, hollow on one side. A concave surface 'caves in' toward the middle — you can literally hear cave inside concave. Its opposite is convex, which bulges outward, so the two are best learned as a pair.

Common Collocations

• 1.concave surface凹面
• 2.concave lens凹透镜

Example Sentences

• 1.

  A concave lens is thinner in the middle than at the edges.

• 2.

  The satellite dish has a smooth concave surface that focuses signals.

• 3.

  Years of use had worn the stone step into a concave curve.

Easily Confused

concave vs convex — concave caves in (hollow, like the inside of a spoon facing you); convex bulges out (like the back of the spoon). Memory hook: concave contains 'cave,' so it's the one that hollows inward.