impulse (impulses plural )
1 n-var An impulse is a sudden desire to do something.
Unable to resist the impulse, he glanced at the sea again...
2 n-count An impulse is a short electrical signal that is sent along a wire or nerve or through the air, usually as one of a series.
3 adj An impulse buy or impulse purchase is something that you decide to buy when you see it, although you had not planned to buy it.
The curtains were an impulse buy.
4 If you do something on impulse, you suddenly decide to do it, without planning it.
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on impulse phrase
Sean's a fast thinker, and he acts on impulse...