The crossword solution for the term 'SOLEMN' is 'agreed!' with the additional solution of 'AMEN' (4 letters). The term 'SOLEMN' is often used to describe a serious, formal, and dignified attitude or atmosphere. In this context, 'agreed!' is an appropriate response to a SOLEMN statement, as it implies that the speaker agrees with the sentiment. The word 'AMEN' is also commonly used in religious contexts to signify agreement with a prayer or statement.