Concave

The moon's orbit is always concave toward the sun.

In the past, a woman was only attractive if her corset created a concave curve.

Concave curbs make little sense.

Concave is the antonym of convex.

You will need a concave lens to take those photos.

It combines concave and convex curves that rise cylindrically, giving the tower a silhouette that will vary depending on the location and angle from which it is viewed.

as concave […] as a worm-eaten nut

Aristotle makes [Fire] to move to the concave of the Moon. - Thomas Salusbury (1661).