Words are one of the elements that constitute a language. From the aspect of language learners, words are the most basic. From the aspect of communication, communication can not be conducted without words, and so do from the aspect of language teaching and research. Therefore, in any period of the whole history, especially in this fast-changing 21st century, research on the linguistic factors and extra-linguistic factors of the appearance of new words has a significant influence on language learners, users, teachers and researchers, who can feel the vicissitudes of the society and life, have a better understanding of current social life in western countries, grasp the popular culture in this modern age, improve their perception and judgment of English, and instantly adjust or correct their social conception to better adapt to the development of the society.

This thesis is structurally composed of six parts. The introduction shows the background and significance of this study. The second part has a literature review on the English Neologisms in the 21st Century, concluding the definition of English Neologisms and related research home and abroad. The third part goes on the research design, containing research questions, subjects, research instruments and data analysis in quantity. Part Four and Part Five explore and analyze the linguistic developmental factors and extra-linguistic developmental factors respectively. Finally, this paper ends with conclusion and limitation.

2. Literature Review

All the living languages are constantly under changes. Each historical period has some unchanging developmental factors that cause the appearance of new forms and meanings of a certain language. Both linguistic and extra-linguistic factors play very important roles in the research of the development of human language.

This chapter is composed of two parts, including the definition of English neologisms and the previous study on this topic. The working definition is based on the research of the emerging factors and changing meaning of many new words in the 21st century. The literature review offered includes domestic studies about English neologisms in the 21st century and a foreign study from the perspective of lexical system of the modern English words and their major development trends. 

2.1 The Definition of Neologisms

According to Oxford English Dictionary (draft revision in 2009), the term neologism is first attested in English in 1772, borrowed from French néologisme. A neologism is the name for a newly coined term, word, or phrase that may be in the process of entering common use, but that has not yet been accepted into mainstream language (Levchenko, 2010: 11). As to Newmark, he defined neologisms as newly-coined lexical units or existing lexical units that acquire new sense (Newmark, 2005: 140).

In this research, a neologism is defined as a word or a phrase that is lately created from sci-tech advancement, economic growth, political evolvement and psychological change and that contains a new meaning which derives from an original word in a new cultural environment.

2.2 Previous Studies of English Neologisms in the 21st Century

2.2.1 Studies Domestic源[自*吹冰^`论\文'网·www.chuibin.com/

After retrieving on the website of CNKI, over 700 essays on English neologisms are found. While there are only no more than 10 essays related to the English neologisms in the 21st century are searched.

The relationship between English neologisms and prototype theory, metaphor theory and conceptual integration theory was briefly researched (Feng Jing and Zang Zhehui, 2012: 132) Zhang Yufang conducted a brief research on the backgrounds of English neologisms in the 21st century from the aspects of society, culture, science and technology, economy, etc (Zhang Yufang, 2010: 216). Besides, there are other four researches about English neologisms in recent decades of years from the perspectives of conceptual integration theory, metaphor recognition, lexicology and word-formation.