知ち音いんちいんMeanings1nounexceptionally close friend; bosom friendA literary and somewhat archaic term for a friend who truly understands one's heart, like a soulmate. In modern Japanese, 親友 or 心の友 are more common.彼かれは私わたしにとって生しょう涯がいの知ち音いんだ。He is a lifelong bosom friend to me.
