- deliberate, voluntary, or intentional: The coroner ruled the death willful murder.
- unreasonably stubborn or headstrong; self-willed.
- the US spelling of wilful
adj.c.1200, “strong-willed,” from will (n.) + -ful. Willfully is late Old English wilfullice “of one’s own free will, voluntarily;” bad sense of “on purpose” is attested from late 14c.