madcap vs impulsive

madcap is a noun but impulsive is not a noun.

Word	Noun	Adjective	Verb	Adverb
madcap	Yes	Yes	No	No
impulsive	No	Yes	No	No

As adjectives, madcap and impulsive are synonyms defined as:

madcap and impulsive: characterized by undue haste and lack of thought or deliberation

Other synonyms of madcap include brainish, hotheaded, impetuous, tearaway.

madcap (noun)	impulsive (noun)
a reckless impetuous irresponsible person

madcap (adjective)	impulsive (adjective)
characterized by undue haste and lack of thought or deliberation	determined by chance or impulse or whim rather than by necessity or reason
	having the power of driving or impelling
	characterized by undue haste and lack of thought or deliberation
	proceeding from natural feeling or impulse without external stimulus
	without forethought