adjective:not willing to do what other people want
adjective:not easily restrained
synonyms: ungovernable, obstinate, stubborn
Examples
He is known for his 'headstrong' behavior.
The child is very 'headstrong'.
Movie quotes
(..) (EXHALES) Hello. Oh, uh... I believe this is yours. (PHILIPPE WHINNYING) She's very headstrong. Do you have children? - (ALL SHOUTING) - (GASPS) PLUMETTE: No one to protect you now, huh? (..)