The term 'BIG HEART' can be broken down into two crossword solutions: ACE (3 letters) and AORTA (5 letters). ACE stands for Angiotensin Converting Enzyme, which is an enzyme that helps regulate blood pressure. AORTA stands for the largest artery in the body, which carries oxygen-rich blood from the heart to the rest of the body. Together, these two solutions represent a big heart, which is a metaphor for having a generous and compassionate nature.