Impulsively is how you do something when a feeling shoves you and you do not stop to weigh it. You impulsively bought the coat. You impulsively told the truth. Same idea as impulsive, but it describes the doing, not the kind of person. It is ordinary English, not stiff. It often suggests a short moment: even a careful person can act impulsively once. Compared with imprudently, this word stresses the sudden wish; imprudently stresses that the choice was unwise. You can do a kind thing impulsively, and you can do a foolish thing impulsively. The word does not, by itself, say the result was bad — though people often reach for it after a mess.