2.1 Origin of Euphemism
Euphemism originated in the Greek prefix “eu-”, it means “good, sounds good”, stem “pheme ” means “speak, statement”. Together, this word literally means “a better word or a pleasant way to speak”. Be a figure of speech, euphemism is considered as “good words” traditionally(Xu Haiming, 1996).

2.2 Definition of Euphemism
There are two popular arguments about the definition of euphemism: 1. Use an unknown vague statement which can make people feel happy instead of a lack of respect for the expression of the meaning of the unpleasant method. 2. Euphemism is mildly or moderate to express of certain facts or ideas in order to reduce its degree of vulgar (Language and Linguistics Dictionary, 2000). Moreover, The Random House College Dictionary(1979) gives “euphemism” a precise definition, that is “the substitution of a mild, indirect, or vague expression for one thought to be offensive, harsh or blunt”.

Euphemism is not only a linguistic concept but also a kind of cultural phenomenon(Wang Huazhen, 2012). First, euphemism is a linguistic concept. It is an important means of communication used on certain occasions. People usually try to avoid the use of language caused the two sides unhappy or damage bilateral relations, instead of using a twists and turns of language forms to expression of ideas and exchange of information(Li Junhua, 2004).

Second, euphemism is a social cultural phenomenon that has infiltrated all aspects of people's daily lives, and reflects a wide range of social phenomena or the people's psychology, such as taking into account the taboo, taboo subject, courtesy, etc.

Euphemism terminology and the euphemism cell rhetoric are not exactly the same. It is a semantic means which people use to express ideas. It is a purpose more than a rhetorical tactics.

2.3 Classification of Euphemism
Euphemism is a language rhetorical taken by the speaker in order to achieve a certain purpose. So we can classify euphemism from euphemism’s social functions and pragmatic purposes. We classify it into altruistic euphemism, encompassing euphemism and self-serving euphemism from pragmatic perspective. Altruistic euphemism tends to other side and their close people or team, taking into account their face. For example, in order to ensure that students and parents are able to withstand psychologically, teachers use “a bit slow” instead of “stupid”, use “need help” instead of “cheap in the exam”, use “should devote more diligently to study” instead of “lazy”, etc. The encompassing euphemism is to make listening to feel the sweet, the speakers seem to be gentle and take care of the face and dignity of the people involved. Such as obesity, disabilities disadvantages, luxury cabin and tourist cabin, etc. Self-serving euphemism is euphemism that speakers speak for their own interests, take care of their own face or the interests of their own groups, or information organizer lies in order to conceal the truth to fool the listeners. Such as war euphemism, Watergate euphemism, etc. Self-serving euphemisms and altruistic euphemism are the two big trends and the middle part of the Pan-profit euphemism(Shao Junhang, 2001).

3 Euphemism and Cross-cultural Communication
The definition of euphemism implies that it’s not easy to understand because of its circuitous saying. Especially in cross-cultural communication, if we do not understand each other's euphemism，we may let the listeners be overwhelmed. Therefore, a correct understanding of the euphemisms in both source language and target language is very necessary. This depends on our knowledge accumulation. In addition, we also need to know the target language culture because language is closely related to culture. There is a very interesting example, the well-known comedy “Huangtupo” by comedy actor Guo Da and Cai Ming’s caused a series of jokes and showed us misunderstanding in cross-cultural communication due to the lack of understanding of each other's local cultures. Although somewhat exaggerated, yet it indeed reflectes the difficulties we will encounter in intercultural communication. Therefore, it is crucial to understand euphemism and its cultural background in cross-cultural communication. 跨文化交际中的英汉委婉语对比研究(2):http://www.youerw.com/yingyu/lunwen_5176.html