adamant
‘unbreakable, invincible’
Lexical development traced from the Tamil root:
E. aðamans, aþamond, adamaund, ademaunde, audamant < O.F. adamant ‘diamond; magnet’ < Lat. adamantem ‘adamant, hardest iron, steel’ < Gk. adamas < a-, an- ‘not’ + daman ‘to conquer, to tame’ < a < ne- < Tamil al