wilful or (N American) willful /wilˈfŭl/

1. Self-willed, obstinate, headstrong
2. Deliberate, intentional
3. Willing (Shakespeare)

Wilfully

wilˈfully adverb

wilˈfulness noun

• undercharging
• underclad
• underclass
• underclasses
• underclassman
• underclassmen
• underclay
• underclays
• under-clerk
• under-clerks
• under-clerkship
• under-clerkships
• undercliff
• undercliffs
• underclothe
• underclothed
• underclothes
• underclothing
• underclub
• underclubbed
• underclubbing
• underclubs
• undercoat
• undercoated
• undercoating