合同中的重要概念可用定义条款（Definitions）加以界定和解释，为产生争议时对合同进行解释提供依据。在定义条款中被定义的词语，通常用大写字母（或首字母大写）、加粗或者加引号表示。

一般情况下，会用定义条款引言引出合同中的定义条款，如：

In this Agreement, unless the contract otherwise requires, the following words or expressions have the meanings assigned to them hereunder.

在本协议中，除另有规定外，下列词语具有本协议项下赋予之含义。

For the purpose of this Agreement, each of the following terms shall have the following meaning respectively：

就本合同的目的而言，下列各用语，分别具有下述意义：

The definitions set forth in Article 1 of this Contract are equally applicable to the Appendix and have the same meanings ascribed to them in this Contract unless otherwise defined in the Appendix.

本合同第一条界定的词语定义同样适用于附件，且本合同中赋予这些词语的含义，与附件这些词语的含义相同。附件中另有界定者除外。

定义条款通常有以下三种作用：

1、避免产生歧义。提高合同语言的精确性。

“Person” means-

(i)a natural person and any corporation or other entity which is given, or is recognized as having, legal personality by the law of any country or territory; or

(ii)any unincorporated association or unincorporated body of persons, whether formed in the united kingdom or elsewhere, including a partnership, joint venture or consortium.

本合同所称“人”为：

(i)自然人、法人公司、或依据任何国家或领域之法律，享有法人资格之实体；或

(ii)在英国或其他地区所组成之非法人组织或非法人团体，包括合伙组织、合资企业或财团组织等。

Person一词，在法律上通常指的是“可以享受权利和承担义务的主体，包括自然人和法人”。在合同中，对该词进行界定，以避免扩大定义范围或造成歧义，产生意图违约的情况。

“Address” means-

(i)in relation to an individual, his usual residential or business address; and

(ii)in relation to a corporation, its registered or principal office in the Republic of China.

“地址”一词：

(i)就自然人而言，指通常之居所或工作场所；

(ii)就公司而言，指位于中华人民共和国之注册所在地或主营业地。

Address一词，表示地址，在合同中，〝地址〞分别在〝自然人〞和〝公司〞两种情况下，需要不同的定义。

2、避免合同在用语上的繁琐。

本框架合同（以下简称“本合同”）由以下签约方于北京订立。

This Framework Contract (hereinafter referred to as “the Contract”) is concluded in Beijing by and between the following parties.

上述卖方、买方单独称为“一方”，合称为“双方”。本框架合同及附件对买卖双方的子公司及关联公司同样适用。

The above Seller and Buyer are individually referred to as a “Party” and collectively referred to as the “Parties”. This Framework Contract and annexes hereto are also applicable to the subsidiaries and affiliates of the Parties.

This Framework Contract定义为the Contract，Seller和Buyer单独定义为Party，合称为Parties。在合同中避免了反复提及This Framework Contract和The Seller and Buyer，而用更为简单清楚的词汇进行替代。

3、提高合同内容的连贯性。

"Patents and Products" shall have the meaning set forth in Clause XX.

“专利和产品”具有第XX条中规定的含义。

"Completion" shall have the meaning set forth in Clause XX.

“交割”具有第XX条中规定的含义。

"Consideration" means the amount calculated with reference to Clause XX.

“对价”指参照第XX条计算的金额。

"Last Day" shall have the meaning set forth in Clause XX.

“截止日”具有第XX条中规定的含义。

这种情况下，定义与解释条款在前，对特定词汇的定义在后文条款中出现，但是

在合同中各项条款出现时被定义的词汇均用加引号表示，方便浏览，也提高了合同内容的连贯性。