noun / verb
lark
LARK/lɑːrk/
A playful activity or behaving playfully for fun.
The friends turn their outing into a lark with an impromptu sack race.

Etymology
Probably shortened from skylark in its playful verb sense. A dialect word for play is another proposal, so the derivation is not certain.
In context
this adventure, though he did not know the English word, was a stupendous lark—a delightful continuation of his old flights across the housetops
More examples
- What starts as a lark becomes a serious hobby.
- The kids lark around in the yard after dinner.
- He auditioned for the play as a lark.
Forms
lark · larks · larked · larking
Similar words
- frolic
- Emphasizes lively, carefree play rather than an amusing adventure.
- prank
- Involves a trick on someone, not merely playful fun.