Headlong and Impromptu

Headlong adjective - Acting or done with excessive or careless speed.

Impromptu and headlong are semantically related. In some cases you can use "Impromptu" instead the word "Headlong" as an adjective or an adverb.

Impromptu adjective - Made or done without previous thought or preparation.

Headlong and impromptu are semantically related. Sometimes you can use "Headlong" instead the word "Impromptu" as an adjective or an adverb.