Heart  n. 1 hollow muscular organ maintaining the circulation of blood by rhythmic contraction and dilation. 2 region of the heart; the breast. 3 a centre of thought, feeling, and emotion (esp. Love). B capacity for feeling emotion (has no heart). 4 a courage or enthusiasm (take heart). B mood or feeling (change of heart). 5 a central or innermost part of something. B essence (heart of the matter). 6 compact tender inner part of a lettuce etc. 7 a heart-shaped thing. B conventional representation of a heart with two equal curves meeting at a point at the bottom and a cusp at the top. 8 a playing-card of the suit denoted by a red figure of a heart. B (in pl.) This suit.  at heart 1 in one's inmost feelings. 2 basically. Break a person's heart overwhelm a person with sorrow. By heart from memory. Give (or lose) one's heart (often foll. By to) fall in love (with). Have the heart (usu. With neg.; foll. By to + infin.) Be insensitive or hard-hearted enough (didn't have the heart to ask him). Take to heart be much affected by. To one's heart's content see *content1. With all one's heart sincerely; with all goodwill. [old english]