willful (adj.) Look up willful at Dictionary.com
also wilful, c.1200, "strong-willed," usually in a bad sense, "obstinate, unreasonable," from will (n.) + -ful. From late 14c. as "eager" (to do something). Mid-14c., of actions, "done on purpose, intentional, due to one's own will." Related: Willfullness.