This course aims at training students to refer to the Arabic Lexicon; old and modern lexical and Semantic dictionaries, acquainting them with the various schools of dictionaries and teaching them how to utilize the great stock of old and modern vocabulary. the course also aims at developing students capability to realize the vocabularies which have several denotation meanings and utilizing this in various linguistic uses , enabling them to acquire the capability to categorize words according to several bases , such as synonymy , antonym ,collection , semantic fields and association , conducting studies on changes which affect words in terms of making some obsolete , others coined and changing the meanings of some words in terms of broadening and narrowing .