Meaning of CONCAVE in English

CONCAVE

con ‧ cave /ˌkɒnˈkeɪv◂, kən- $ ˌkɑːnˈkeɪv◂, kən-/ BrE AmE adjective

[ Date: 1500-1600 ; Language: Latin ; Origin: concavus , from com- ( ⇨ COM- ) + cavus 'hollow' ]

a concave surface is curved inwards in the middle OPP convex :

a concave lens

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.