Definition of "ingenuous"

"Do you mean to say you didn't leave your wife for another woman?""Of course not.""On your word of honour?"I don't know why I asked for that. It was very ingenuous of me.

1919, W[illiam] Somerset Maugham, “ch. 12”, in The Moon and Sixpence, [New York, N.Y.]: Grosset & Dunlap Publishers […]

The apparent contradictions in his behaviour should therefore be discounted as ingenuous attempts to extricate himself from the consequences of an intellectual position which he once adopted but was never really his by intimate conviction.

1965, New Left Review, page 86

[…] Semitic agitation by stating 'the truth' in terms of facts and figures, the practice of self-criticism represented a well-intended but ingenuous effort to defend Jewry against anti-Semitism.

1978, G. Lebzelter, Political Anti-Semitism in England 1918–1939, page 150

There was nothing more I dared say. My ingenuous attempts to lie my way out of trouble had only served to get me in deeper and deeper.

2012, Hester Rowan, The Linden Tree

[H]is Grace’s Man at his club, in company doubtless with other Men of equal social rank, talks over his master’s character and affairs with the ingenuous truthfulness which befits gentlemen who are met together in confidence.

1848 November – 1850 December, William Makepeace Thackeray, chapter 37, in The History of Pendennis. […], volumes (please specify |volume=I or II), London: Bradbury and Evans, […], published 1849–1850