2.0. Semantics…………………………………………………………………………….…….…9 2.1. Introduction……………………………………………………………………….…..….….24 2.2. Trends in lexicology………………………………………………………………..…..……28 2.3. Vocabulary knowledge in L2………………………………………………………………..33 2.4. Experiments on vocabulary issues……………………………………………………..….…39 2.5. Experiments on English cognate words………………………………………………….….42 2.6. Experiments on Iranian EFL learners’ knowledge of English vocabulary………………..…47 2.7. Summary…………………………………………………………………………………..…52 CHAPTER3: METHODOLOGY 3.0. Introduction…………………………………………………………………………….……57 3.1. The design of the study………………………………………………………….………..…57 3.2. Participants………………………………………………………………………..……..….59 3.3. Materials………………………………………………………………………………….…60 3.4. Procedure……………………………………………………………………………………60 3.5. Methods of Analyzing Data…………………………………………………………………60 3.6. Summary……………………………………………………………………………..………61 CHAPTER4: RESULTS AND DATA ANALYSIS 4.0)Introduction ……………………………………………………………………………….…62 4.1) Descriptive Statistics……………………………………………………………….………..62 4.3) Inferential Statistics…………………………………………………………………..….…..64

4. 4. 4) Summary…………………………………………………………………………………….69

CHAPTER5: DISCUSSIONS AND IMPLICATIONS 5.0. Introduction………………………………………………………………………………….70 5.1. General Discussion………………………………………………………………………….70 5.2. Implications of the study………………………………………………………….………….71 5.3. Limitations of the study…………………………………………………………….………..71 5.4. Suggestions for further Research…………………………………………………………….72 REFRENCES …………………………………………………………..…………………..…..73 LIST OF APPENDICES ……………………………………………………………………….76 List of Tables Title  Page Table (4.1) .Descriptive statistics for the proficiency test………………….……………………..63 Table (4.2) . Number of students participated in pre-test and post-test case………………….….63 Table (4.3) .Descriptive statistics for the pre-test and post-test………………………………..….64 Table (4.4) Levine’s Test of Equality of Error Variances…………………………….……………66 Table (4.5) Tests of Between-Subjects Effects …………………………………………………..66 Table (4.6) Mean and corrected Mean of lexical knowledge ……………………..……….….…67 Table (4.7) Sum of Analysis of covariance