The term 'HOW TRUE!' can be expressed in four different ways using the solutions of a crossword puzzle. The first solution is 'AMEN' which is a Hebrew word meaning 'so be it' and is often used to express agreement or acceptance. The second solution is 'IAGREE' which is a simple way of expressing agreement. The third solution is 'ICANRELATE' which means to understand or empathize with a situation. Finally, the fourth solution is 'YOURENOTKIDDING' which is a phrase used to emphasize the truthfulness of a statement. All of these solutions are ways of expressing agreement or understanding with the sentiment of 'HOW TRUE!'