The term 'of sound mind' is a legal phrase used to describe someone who is mentally capable of making decisions. This phrase can be broken down into four crossword solutions: SANE (4 letters), LUCID (5 letters), STABLE (6 letters), and COMPOSMENTIS (12 letters). SANE means having a healthy mind, LUCID means clear and easily understood, STABLE means not easily changed or disturbed, and COMPOSMENTIS means having mental composure. Together, these words describe someone who is mentally capable of making decisions.