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simple; artless; naive; unsophisticated
素樸な疑問から始まった研究が大発見につながった。
Research that began with a simple question led to a major discovery.
この村の人々は素樸で温かい人柄が多い。
Many people in this village have a simple and warm personality.
素樸な味わいの手料理が一番おいしいと思う。
I think simple, home-cooked food tastes the best.