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
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. 2012