insincerity; dishonesty; bad faith
Refers to a lack of sincerity or honesty in attitude or behavior. Often used in formal or written contexts to describe untrustworthy conduct.
I was disappointed by his insincere attitude.
Bad faith in a contract is not tolerated.
Compound of 不 (fu-, 'not') + 誠意 (seii, 'sincerity, good faith'). The exact historical derivation is uncertain, but the word follows a standard Sino-Japanese pattern for forming abstract nouns.