Translation guide
The quality of being disloyal, unreliable, or untrustworthy, especially in personal relationships or duties.
Expressing unfaithfulness or betrayal, especially in romantic or close personal relationships.
Describing a person who cannot be trusted to keep promises or fulfill obligations.
Referring to absence of belief or loyalty to a religion or deity.
The English noun 'faithlessness' is abstract and rarely used in casual speech. In Japanese, it's more natural to use specific words like 浮気 (cheating) or phrases like 当てにならない (unreliable) depending on context, rather than a single abstract noun.
A general term for insincerity or lack of faithfulness, often used in personal relationships. It implies a breach of trust.
彼の不誠実な態度に失望した。
I was disappointed by his faithless attitude.
Specifically refers to cheating or having an affair. Very common in romantic contexts.
彼女の浮気が原因で別れた。
We broke up because of her infidelity.
A change of heart, often implying fickleness or loss of affection. Can be used for faithlessness in love.
彼の心変わりは突然だった。
His change of heart was sudden.
A formal or literary term for betrayal of trust, often used in serious contexts like politics or business.
その行為は背信行為とみなされた。
That act was regarded as an act of faithlessness.
Also used for general unreliability and lack of integrity beyond romantic contexts.
彼は不誠実だから約束を守らない。
He is faithless, so he doesn't keep his promises.
Irresponsibility; often used when someone fails to fulfill duties or commitments.
彼の無責任な行動に皆が困っている。
Everyone is troubled by his faithless behavior.
A colloquial phrase meaning 'unreliable' or 'not to be counted on'. Natural in everyday speech.
彼は当てにならないから、頼まないほうがいい。
He's faithless, so you'd better not ask him.
Lack of religious faith or belief. Neutral term.
彼の不信仰は家族を悲しませた。
His faithlessness saddened his family.
Can also be used in religious contexts for apostasy or betrayal of faith, but is formal/literary.
彼は神への背信を告白した。
He confessed his faithlessness to God.