na-adjective, noun
overly polite; excessively polite; polite to a fault
Describes language or behavior that is so excessively polite it becomes unnatural, awkward, or even sarcastic. Often used critically.
あの店員のバカ丁寧な接客は、かえって不自然に感じる。
That clerk's overly polite service feels rather unnatural.
彼は
He uses excessively polite language with his boss, so his colleagues are a bit put off.