Brighten (verb)

1. To make or become brighter or more cheerful.
2. To make or become more lively or cheerful in appearance or mood.

Origin:

From bright + -en, first recorded in the 14th century.

Examples:

1. The sun began to brighten the room.
2. She brightened up the room with some colorful flowers.
3. He brightened up when he saw his friends.
4. The news brightened her mood.
5. She brightened up the room with her presence.