Is “Concave” a Scrabble word?

1.A concave surface or curve.

2.The vault of the sky.

3.One of the celestial spheres of the Ptolemaic or geocentric model of the world.

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

1.To render concave, or increase the degree of concavity.

1.Curved like the inner surface of a sphere or bowl

2.(of a polygon) not convex; having at least one internal angle greater than 180 degrees.

3.(of a real-valued function on the reals) satisfying the property that all segments connecting two points on the function's graph lie below the function.