The word concave means curving in or hollowed inward. The term is most commonly used to refer to:

• Concave lens, a lens with inward-curving (concave) surfaces.
• Concave polygon, a polygon which is not convex.
• Concave function, a type of function which is related to convex functions.

In addition, the term concave upwards is used for convex functions, and concave downwards for concave functions.

See also

• Convex — the opposite of concave.

Mathematical disambiguation

Konkav | Konkav | Konkaavisuus | פונקציה קעורה | Concaaf | Konkav