1
be unfaithful to someone
常用于指对配偶或伴侣不忠。
She was unfaithful to her husband.
她对丈夫不忠。
不忠实的；不诚实的
先理解核心含义，再看它在真实句子里的用法。
不忠实的；不诚实的
not true to duty or obligation or promises
She was unfaithful to her husband.
她对丈夫不忠。
没有宗教信仰的。
Not having religious faith.
不守信用的；不忠的；不忠诚的。
Not keeping good faith; disloyal; not faithful.
通奸的；不忠的。
Adulterous.
不诚实或不正直的。
Not honest or upright.
She found evidence that her partner had been unfaithful with a colleague.
她发现证据表明她的伴侣与同事有染。
The spy was executed for being unfaithful to his country.
这名间谍因背叛祖国而被处决。
He was unfaithful to his promise to help me move house.
他违背了帮我搬家的承诺。
常用于指对配偶或伴侣不忠。
She was unfaithful to her husband.
她对丈夫不忠。
用于指不履行义务或承诺。
He was unfaithful in his duties as a manager.
他在经理职责上不诚实。
Not this
He unfaithful to his wife.
Use this
He is unfaithful to his wife.
错误地将形容词 unfaithful 用作动词，缺少系动词。应使用 be unfaithful to 结构。
Not this
She was unfaithful with her husband.
Use this
She was unfaithful to her husband.
介词搭配错误，与 unfaithful 搭配的介词应是 to，表示对某人不忠，而非 with。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
对某人不忠
She was unfaithful to her boyfriend for months.
她对她男朋友不忠有好几个月了。
不忠的丈夫
After years of suspicion, she finally left her unfaithful husband.
在怀疑多年后，她终于离开了不忠的丈夫。
不忠实于原文的
The translator's version is unfaithful to the original in several passages.
译者的版本在几处段落中不忠实于原文。
不忠于原文的译文
An unfaithful translation may mislead readers about the author's intention.
不忠实的译文可能会误导读者理解作者的意图。
我不想不忠，但你不在身边时，真的很难保持忠实。
This is the chorus of Rihanna's 2006 hit single 'Unfaithful'. In the song, the singer struggles with the temptation to cheat on her partner, and the word 'unfaithful' highlights the sense of being disloyal or adulterous.
这是蕾哈娜2006年热门单曲《Unfaithful》的副歌。歌曲中，歌手挣扎于背叛伴侣的诱惑，'unfaithful'一词突出了不忠诚或不忠贞的含义。
Use unfaithful naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
un-（不）+ faithful（忠诚的）＝不忠诚的；记住：对伴侣或承诺失去faith（信任）就是unfaithful。
语域：neutral 常见场景：in a marriage or relationship、in formal or serious writing、when discussing loyalty or betrayal 该词通常用于正式或严肃的场合，多指婚姻或恋爱关系中的不忠，也可泛指不忠诚、背信弃义。日常口语中较少使用，比较常见于书面语、新闻报道或法律语境。
发音对照：unfaithful /ʌnˈfeɪθfəl/ 与 faithful /ˈfeɪθfəl/ 完全押韵（重读元音 /eɪ/ 及之后的 /θfəl/ 相同）；wasteful /ˈweɪstfəl/ 和 graceful /ˈɡreɪsfəl/ 虽有相同的重读元音 /eɪ/，但 /stf/、/sf/ 与 /θf/ 不同，不押韵；untruthful /ʌnˈtruːθfəl/ 拼写结构与 unfaithful 相似（un- + … + -ful），但重读元音是 /uː/，不押韵；useful /ˈjuːsfəl/ 和 helpful /ˈhelpfəl/ 只共享非重读后缀 -ful /fəl/，也不押韵。
Dictionary facts from ECDICT, WIKTIONARY.