Home words to describe someone Adamantine words to describe someone Adamantine 1196 0 Facebook Twitter Pinterest WhatsApp Adamantine- Definition: ad·a·man·tine [àdd? mán t?n, àdd? mán t?n, àdd? mántin] adjective (literary) 1. unyielding: extremely hard or unyielding 2. hard and brilliant: like a diamond in hardness and brilliance