A sweetheart is someone you care about deeply in a romantic way, like a boyfriend or girlfriend. When two people are sweethearts, they have special feelings for each other that go beyond ordinary friendship. You might see teenagers holding hands and realize they're sweethearts, or hear someone say, “those two have been sweethearts since middle school.”

The word also describes someone with an exceptionally kind and gentle nature. If your grandmother says, “that girl is such a sweetheart,” she means the person is thoughtful, considerate, and pleasant to be around. A teacher might call a helpful student a sweetheart, or you might describe a friend who always shares their lunch as “a real sweetheart.”

People sometimes use sweetheart as a term of affection when talking to someone they love, like a parent saying, “good morning, sweetheart,” to their child. In old movies or books, you'll often hear romantic partners call each other sweetheart.