Definition of on/as a lark
- She entered the race on/as a lark.
: any of a family (Alaudidae) of chiefly Old World ground-dwelling songbirds that are usually brownish in color
: a source of or quest for amusement or adventure
: to engage in harmless fun or mischief
What made you want to look up on/as a lark? Please tell us where you read or heard it (including the quote, if possible).