Sweetheart (noun)

1. A person to whom one is romantically attached or has affection for.
2. A term of endearment used to address someone one loves or cares for.

Origin:

Sweetheart, an affectionate term of endearment for a loved one, originated in the 16th century.

Examples:

1. She's my sweetheart, and I love her with all my heart.
2. He called his wife sweetheart and gave her a kiss on the cheek.
3. They've been sweethearts since they were teenagers.
4. She's the sweetheart of the family, always bringing joy and laughter.
5. He sent a bouquet of flowers to his sweetheart on their anniversary.