Tacit understanding or telepathy; mutual understanding without words — when people naturally know each other's thoughts or feelings.
長年連れ添った夫婦は、以心伝心で会話しなくても意思が通じることが多い。
Long-married couples often understand each other without words — a kind of tacit understanding.
チームワークが良く、メンバー同士は以心伝心で動いている。
The team works so well that the members move with tacit understanding.
彼とは以心伝心のようで、指示しなくてもやるべきことをやってくれる。
With him it's almost telepathic — he does what needs to be done without being told.
In Buddhism (especially Zen), the non-verbal transmission from master to disciple — passing essential teachings directly heart-to-heart beyond words.
禅では経典だけでなく、師から弟子への以心伝心が重視される。
In Zen, emphasis is placed not only on scriptures but also on the master's non-verbal transmission to the disciple.