ingenuous C2

/ɪnˈd͡ʒɛn.ju.əs/ Innocent and trusting in a simple, honest way; not suspicious of others.

ingenue C2+

/ˈænʒəˌnu/ an innocent or unsophisticated young woman, especially as a stage role

ingenuousness C2+

/ɪnˈdʒɛnjuəsnəs/ the quality of being frank, innocent, and free of guile