What is 'strong mind' in Latin?

Corpus firmum is one Latin equivalent of 'strong body'. In the Word by Word translation, the noun 'corpus' means 'body'. The adjective 'firmum' means 'strong'.

Corpus lacertosum is another Latin equivalent of 'strong body'. In this case, the meaning is the same, but the emphasis differs. The adjective 'lacertosum' stresses the muscular character of that body strength.