Rapport
Etymology
From French rapport "connection, correspondence," from rapporter "to bring back," from re- plus apporter, from Latin apportare ("ad-" toward plus "portare" to carry). The idea is of something carried back and forth between two parties — the channel, not the spark.
noun · /ra-POR/
A relationship of easy mutual understanding in which communication flows smoothly.
What it names
A handle for the built, workable trust between people — something you establish and maintain, not something that simply strikes.
Example
A good interviewer spends the first two minutes building rapport so the hard questions land as curiosity, not attack.
Related idea
Distinct from chemistry: rapport is the working relationship you can deliberately construct with almost anyone, while chemistry is the involuntary charge that either exists or does not. You can have rapport without chemistry, and chemistry without any real rapport.