失信的英文：
a breach of faith
break faith
break one's word
dishonour
fall down

参考例句：

It isn't good for one to lie and Break one's word.
一个人说谎失信是不好的。

I would never Break a promise that I'd made to a friend.
我绝不对我的朋友失信。

"she reproached him for his breach of faith, earnestly as he protested his innocence;"
"凤姐故意抱怨他失信,贾瑞急的赌身发誓."

Commerce dies the moment, and is sick in the degree in which men cannot trust each other.
一旦人无法互信，商业就停滞了；失信的程度有多严重，商业失序的程度就有多严重。

breach是什么意思：
n.[C]
1.破坏，违犯；违反，不履行；（对他人权利等的）侵害
2.破裂；裂口，（尤指炮火轰开的）缺口
3.（友好关系的）决裂；裂痕
4.中断，中止
5.（海浪的）冲击；（冲击海岸、防波堤等的）激浪，碎波
6.鲸跃
v.[T]
1.破坏；违反
2.攻破，突破；撕裂，在...造成缺口
v.[I]
（鲸）跃出水面

heal the breach
弥合裂痕,调停

It was a gross breach of protocol.
这是粗暴违反外交礼节的行为。

to make a breakthrough; to breach
攻破

faith是什么意思：
n. 信任，相信，宗教信仰，宗教，诚意，善意

As faithful as a dog.
像狗一般的忠诚。

"in faith (=by my faith, upon my faith)"
实在!说实话!说真的!的确!

Faith, which does not doubt is a dead faith.
没有怀疑的信念是无生命的信念。

break是什么意思：
v. 打破；弄坏；兑开；违反；破解；使破产；突破；中断；削弱；突发；破晓
n. 破裂；中断，休息；骤变

to devastate; to break
使垮掉

Did you break your toy?
你弄坏你的玩具了吗？

break [lift, raise] a blockade
冲破 [解除] 封锁