Honest and straightforward without any tricks or deception; innocent and trustworthy.
From guile (deception) + -less suffix meaning 'without.' The term emerged in English around the 1600s to describe someone free from deceit, the opposite of someone full of cunning.
Children are often described as 'guileless,' which is why there's a universal human instinct to protect them—we've learned over thousands of years that innocence and trustworthiness make us vulnerable in a complex world.
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