Duhaime's Law Dictionary Willfully Definition: Acting voluntarily, deliberately and intentionally. Related Terms: Knowingly "Willfully means that a defendant acted knowingly, deliberately, and intentionally as contrasted with accidentally, carelessly or unintentionally."Willfully means a voluntary, intentional violation of a known legal duty. In other words, the defendant must have acted voluntarily and intentionally and with the specific intent to do something that the law forbids; that is to say, with a purpose either to disobey or disregard the law." Compare with Legal Definition of Knowingly. REFERENCES:US v De Castro-Font, 587 F. Supp. 2d 372 (2008; Footnote #1) Categories & Topics: Duhaime's Criminal Law Dictionary Always looking up definitions? Save time with our search provider (modern browsers only) If you find an error or omission in Duhaime's Law Dictionary, or if you have suggestion for a legal term, we'd love to hear from you!