当事人的英文：
party
persons involved or implicated

参考例句：

Richard Roe
【律】诉讼中不知姓名的当事人

The lawyer pleaded his client's youth in extenuation of the crime.
律师以其当事人年少为由请求减轻其罪行。

In case of bilateral breach, the parties shall assume their respective liabilities accordingly.
当事人双方都违反合同的，应当各自承担相应的责任。

Litigants or legal representatives may entrust one or two persons to represent them in the action.
当事人、法定代理人可以委托一至二人作为诉讼代理人。

Talks between lawyer and client are privileged
律师与当事人的谈话是机密的。

A lawyer acts on behalf of his client.
律师作为当事人的代言人。

Talks between lawyer and client are privileged.
律师与当事人的谈话是机密的。

Interpretation may be provided where a litigant so requests, and the litigant shall bear the costs therefrom.
当事人要求提供翻译的，可以提供，费用由当事人承担。

A contract may be amended if the parties have so agreed
当事人协商一致，可以变更合同。

Plead a client's case
为某一当事人的案子辩护

party是什么意思：
n. 党，党派；队，社交聚会一方，参与者；餐馆食客
adj. 社交聚会的，党派的，共有的，共用的
v. 参加社交聚会；尽情欢乐，为...举行社交聚会

Ours is a great Party, a glorious Party, a correct Party.
我们的党是一个伟大的党，光荣的党，正确的党。

They are the backbone of the party.
他们是政党的骨干。

an orgy of parties
一连串宴会的狂欢

involved是什么意思：
adj. 参与的；专心于…的；复杂难懂的；关系暧昧的；涉及的
v. involve的过去式和过去分词；牵涉

Involved or intricate, as in structure; complicated.
复杂的在结构中牵扯较多的或错综复杂的；复杂的

It's derivation involved no approximation.
这种近似方法的适用性将在后面再讨论。

There was no motive of sexual involvement.
没有牵涉性方面的动机。