"ingenuous" in the adjective sense
1. ingenuous, artless
characterized by an inability to mask your feelings not devious
"an ingenuous admission of responsibility"
2. innocent, ingenuous
lacking in sophistication or worldliness
"a child's innocent stare"
"his ingenuous explanation that he would not have burned the church if he had not thought the bishop was in it"
Source: WordNet® (An amazing lexical database of English)
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