v. phr. 1. To talk about your feelings honestly; confide in someone. After going around worrying, Mary opened her heart to her mother. John felt much better after he opened his heart to Betty. 2. To be sympathetic to; give love or help generously. Mrs. Smith opened her heart to the poor little boy. After the moving speech by the UN official, the people opened their hearts to the poor people of India.
Compare: OPEN HEART, WEAR ONE'S HEART ON ONE'S SLEEVE.