na-adjective, noun
pure; innocent; naive; pure-hearted
Describes a person's character or heart as genuinely pure, innocent, and without malice; often carries a positive, unspoiled nuance. Can also imply a certain naivety or lack of worldly experience.
彼女の純真な笑顔に心が和んだ。
Her innocent smile warmed my heart.
子供の純真さは時に大人を
The purity of children sometimes startles adults.
彼は純真すぎて、人を疑うことを知らない。
He is so naive that he doesn't know how to doubt others.
純粋 emphasizes genuineness, unadulterated state, or single-mindedness, and can apply to objects or abstract concepts (e.g., 純粋な水, 純粋な気持ち). 純真 is more specifically about a person's innocent and pure heart.
無邪気 highlights childlike innocence and playfulness, often without any negative connotation. 純真 can imply a deeper, more fundamental purity of character, sometimes with a hint of naivety.
Compound of 純 (pure, genuine) and 真 (truth, reality). The combination conveys the idea of a heart or character that is genuinely true and untainted.