means A relationship of mutual understanding and ease, in which people feel connected and in sync with one another.

from From French rapport, 'connection, relation,' from rapporter 'to bring back, refer'—built from re- ('back') plus apporter ('to bring'), itself from Latin apportare (ad- 'to' + portare 'to carry'). So at its Latin root it's about carrying something to and fro: rapport is the thing two people keep carrying back to each other until it becomes a shared rhythm. English borrowed it intact in the 17th century, accent and all.