To make something more pleasant or attractive by adding or changing something. She decided to freshen the room with a new coat of paint.
To make something cleaner or more fragrant. He used air freshener to freshen the air in the living room.
To make oneself feel more awake or alert. After a long flight, she went to the restroom to freshen up before the meeting.
Of wind, air, or weather: to become stronger, cooler, or fresher. The breeze freshened as dusk fell.