All 5 Uses

impetuous
in
The Pioneers, by Cooper
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Effingham was by nature indolent, confiding, and at times impetuous and indiscreet; but Marmaduke was uniformly equable, penetrating, and full of activity and enterprise.†
Chpt 2 *

impetuous = impulsive (acting suddenly without much thought)
A narrow current rushed impetuously from its bosom at the open place we have mentioned, and was to be traced for miles, as it wound its way toward the south through the real valley, by its borders of hemlock and pine, and by the vapor which arose from its warmer surface into the chill atmosphere of the hills.†
Chpt 3

impetuously = impulsively (acting suddenly without much thought)
Something like a miracle was wrought in our favor, for enormous shoals of herrings were discovered to have wandered five hundred miles through the windings of the impetuous Susquehanna, and the lake was alive with their numbers.†
Chpt 21

impetuous = impulsive (acting suddenly without much thought)
"But not you—not you," said the impetuous Elizabeth— "not you, dear girl, you have never known the misery that is connected with poverty."†
Chpt 28
"I can," cried the youth, with an impetuosity that startled his companion.†
Chpt 31

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.