On a whim

Meaning

Act impulsively without planning.

Usage

Used to describe spontaneous acts.

Origin & History

Origins and dates here are approximate summaries. Many idioms have disputed or unknown origins, and not every date has been checked against a historical dictionary, so treat specific dates and stories as a starting point rather than a citation.

Whim is short for whim-wham, meaning a capricious fancy.

From the 18th century onward.