1.所谓定义，就是在交流中清晰表述某一事物的外观形状，本质特性等。最具有代表性的就是字典中对书面词语的定义。由于口语交流有严格的时间限制，所以在短时间内用简洁的英文依照英美人的思维方式用口头给出准确的定义在口语交流中显得尤为重要。

　　示范1：A synonym is one of two or more words // of the same language//having//the same or nearly the same essential meaning.

　　中文中我们说：“同义词指的是某种语言中基本意思相同或相近的两个或更多的词语。”

　　示范2：To jump is to spring // free from the ground by the muscular action of the feet and legs or, as in some animals, the tail.

　　中文中我们说：“跳是借助脚和腿--某些动物也用它们的尾巴--的肌肉运动来跃离地面。”

　　示范3：Breathing is the process // of taking oxygen//into//an organism or body and giving off carbon dioxide.

　　中文中我们说：“呼吸是有机体或生物体吸入氧气排出二氧化碳的过程。”

　　3.定义时应按照所定义的对象的词性来组织口头语言：定义名词用另一名词或名词短语；定义动词用另一动词并且两者都以不定式(to)开头；定义形容词用另一形容词或短语；定义副词用另一副词或短语。例如：(名词)A physician is a person who is skilled in the art of healing. (动词)To demonstrate is to show by reasoning or proof. (形容词)Healthy means being in a state of health or enjoying health. (副词)Cowardly means in the manner of a coward.

　　4.定义应当完整、简明、易懂。

　　5.定义时应避免重复使用同一个词，以免造成同义反复。

　　例如：(错)To approve is the act of approving something.

　　(对)To approve is to confirm formally.

　　6.定义时避免用when, where, what等引导的短语。

　　例如：(错)Illness is when you are sick.

　　(对)Illness is a state of disordered health.

　　(错)A bed is//where//you sleep.

　　(对)A bed is a piece of furniture to sleep or take rest in or on.