wilful or (N American) willful /wilˈfŭl/

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

Wilfully

wilˈfully adverb

wilˈfulness noun

• underestimates
• underestimating
• underestimation
• underexpose
• underexposed
• underexposes
• underexposing
• underexposure
• underexposures
• underfed
• underfeed
• underfeeding
• underfeeds
• underfelt
• underfelts
• underfinished
• under fire
• underfire
• underfired
• underfires
• underfiring
• underfish
• underfished
• underfishes
• underfishing