All 4 Uses of

impetuous

in

Moby Dick

For however eagerly and impetuously the savage crew had hailed the announcement of his quest; yet all sailors of all sorts are more or less capricious and unreliable--they live in the varying outer weather, and they inhale its fickleness--and...
Chpt 46-48 *

impetuously = impulsively (acting suddenly without much thought)

…of common occurrence in this kind of life; considering that at the superlatively critical instant of going on to the whale I must resign my life into the hands of him who steered the boat—oftentimes a fellow who at that very moment is in his impetuousness upon the point of scuttling the craft with his own frantic stampings; considering that the particular disaster to our own particular boat was chiefly to be imputed to Starbuck's driving on to his whale almost in the teeth of a squall,…†
Chpt 49-51

I see!' impetuously exclaimed Don Pedro, spilling his chicha upon his silvery ruffles.†
Chpt 52-54

"Man my boat!" cried Ahab, impetuously, and tossing about the oars near him—"Stand by to lower!"†
Chpt 100-102

Definition:

(impetuous as in: an impetuous decision)
impulsive (acting suddenly without much thought) -- often with an unfortunate consequence