1. a person with whom one is romantically involved
2. a kind, lovable, or endearing person
3. used as a term of endearment when addressing someone

Examples

• She’s been dating her sweetheart for three years.
• He married his high school sweetheart.
• Thanks for helping me, sweetheart.
• Their grandmother is such a sweetheart to everyone.
• Come here, sweetheart, and give me a hug.
• My sweetheart surprised me with flowers on my birthday.
• The old man at the store is a real sweetheart.