【Abstract】Polysemy is very common in English vocabulary. It is essential to analyze the structure， features and language context of polysemy for language learner. For the four different reasons：shift of application in different fields；mutual transformation between common words and specialized words；ellipsis in language use and the reason explained in cognitive theory， polysemy comes into being.

【Key words】English； Polysemy； language context

I. Causes of polysemy

Polysemy is the common feature in the whole natural language， especially in English. With the development peoples needs of recognizing and explaining the world，the problem of shortage of already-existed words arises. There are four different reasons.

1. shift of application in different fields

This is the main cause of polysemy. Words have many meanings in different language context. Some are temporary， while some are permanent。Such as “mouth”，the original meaning is the mouth of animal， Now it not only can refer to humans mouth but also can means the export of river and the entrance to the cave.

2. Mutual transformation between common words and Specialized words

In some sense， this is one of the shifts of application. “Mouse” becomes the mouse locator in computer terminology while the original meaning is “a kind of animal”. Word meanings vary with social environment in different field. For mathematicians， operation means “calculation”， while it is naturally understood as “military action” for soldiers.

3. Ellipsis in language use

The use of the word is limited by language context， so it is not random.That is to say， they are always used with collocation of certain words. In the process of the use of collocations， their meanings are shifted in some ways， and then the two words have the same meaning. ‘Capital city， ‘capital funds and ‘capital letter. Because the three phrases commonly appear and used frequently， the last word is omitted and its meaning shifted to ‘capital （city， fund， and letter）.

4. The reason explained in cognitive theory

It is more acceptable to explain it in the usage of figurative languages （metaphor and metonymy） .It gives the additional meanings without losing the original meaning. Prototype theory was proposed by Eleanor Roach， an American psychologist in the middle of 1970s.This theory has great influence on the study of polysemy. In terms of polysemy， cognitive linguistics theories think that there are multiple meanings under each key word. And these meanings are associated.

II. Linguistic context

1. The influence of broad context on words

The word meaning is very much influenced by what circumstances we used a word. For example， “its a difficult operation”. How can we understand the meaning of ‘operation in different circumstances？ It can all dependent on where we say it. When we say it in the hospital， it means ‘surgery； when we say it in the factory， it means ‘handle. It can all dependent on where we say it. ‘Ambition has no derogatory sense in western country， but it is a derogatory word in Chinese meaning. There are endless examples.

2. The influence of narrow context on words

The excusive context also called language context. The language context is the situation in which the source test is produced， and the source texts are located. The emergency of vocabulary in context is not arbitrary， but always in a certain structure， restricted by the grammatical structures and vocabulary structure. Grammatical-text， namely the grammatical context of the vocabulary refers to the word framework of grammar. Lexical-text is the vocabulary context of the vocabulary. And its the embodiment of grammatical structure. For example， we can say： have a dinner， have a rest， have a party， and have a baby and so on. The word ‘have has different meanings in different context. In the phrases ‘get to do something and ‘get someone to do something. The word ‘get has different meanings because of the grammatical context.

III. The impacts of polysemy in English

As a common phenomenon in English， polysemy has brought lots of impacts to the English learners. There is no doubt that they will meet a lot of problems caused by polysemy. Context plays a crucial role for the elimination of polysemy ambiguities in the course of usage. Learners should focus on cultivating the ability to understand polysemy in English learning. We should combine the new words and grammatical context in a way which is suitable for learners' level and pay attention to polysemy in the real meaning of life. The founder of the English language school Firth once said： Each word when used in a new context is a new word. It will have a huge boost for language teaching and language use if you master as well as understand its exact meaning in the article.

參考文獻：

[1]段滿福.談英語一詞多義現(xiàn)象[J].內(nèi)蒙古大學(xué)學(xué)報，2004（3）.

[2]林承璋.英語詞匯學(xué)引論[M].武漢大學(xué)出版社，2001.

作者簡介：李俊飛（1991.4.29-），女，漢族，河南人，文學(xué)院漢語國際教育碩士研究生在讀，哈爾濱師范大學(xué)，文學(xué)院，漢語國際教育。