concave
C1Adjektiv/US /kɑnkˈeɪv/ känk-ĀV; UK /kɑnkˈeɪv/ känk-ĀV/
Hollow and curved or rounded; vaulted; -- said of the interior of a curved surface or line, as of the curve of the of the inner surface of an eggshell, in opposition to convex; as, a concave mirror; the concave arch of the sky.
