Lark (noun)

1. A small songbird with a short tail and a melodious song, typically active at dawn and dusk.
2. An activity or outing done for pleasure, especially one that is impromptu or spontaneous.

Origin:

Old english larc, of germanic origin; related to dutch lork and german lerche.

Examples:

1. He was up early to watch the larks singing in the fields.
2. The lark was a common sight in the countryside.
3. The lark's song was one of the first sounds of spring.
4. The group of friends decided to go on a lark and go camping for the weekend.
5. The couple's trip to Paris was a lark, a spontaneous decision made on a whim.