Headstrong

Part of speech: adjective (a.)

1. Not easily restrained; ungovernable; obstinate; stubborn. Not let headstrong boy my will control. Dryden.

2. Directed by ungovernable will, or proceeding from obstinacy. Dryden.

Synonyms: Violent; obstinate; ungovernable; unratable; stubborn; unruly; venturesome; heady.