Both Uses

impetuous
in
Brideshead Revisited
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I only arrived in London yesterday, and heard quite by chance at luncheon that you were having an exhibition, so of course I dashed impetuously to the shrine to pay homage.†
p. 308.9 *

impetuously = impulsively (acting suddenly without much thought)
I knew nothing of finance, but I heard it said that his dealings were badly looked on by orthodox Conservatives; even his good qualities of geniality and impetuosity counted against him, for his parties at Brideshead got talked about.†
p. 341.7

impetuosity = impulsiveness (the trait of acting suddenly without much thought)

Definitions:

(1) (impetuous as in: an impetuous decision)
impulsive (acting suddenly without much thought) -- often with an unfortunate consequence
(2) (meaning too rare to warrant focus)
In historic literature, impetuous often refers to any rapid, forceful, and/or violent movement.