ingenuous
Ingenuous (adjective) means Innocent and trusting to the point of seeming naive, particularly about people's motives. Example: “It was ingenuous of him to hand over the deposit without a contract.”
How to use ingenuous
Learner’s notesIn plain EnglishTrusting and honest in a way that can leave you open to being tricked.
Formal and literary; the negative form disingenuous is now heard far more often.
Link ingenuous to ingénue, the innocent young woman of the theatre, and ingenious to engine and engineer.
Trace the full origin ↓Fill the gap
Can you complete this real example?
It was _____ of him to hand over the deposit without a contract.
Etymology
From Latin ingenuus, meaning native-born or free-born, and hence noble or frank in character.