Vocabulary is an independent discipline, because it has special research objects, word. Phonetics is the only research speech, semantics, but only semantic study of speech and semantic words not simple addition, it is the unity of sounds and meanings. The study of the voice of the isolated words meaning and cannot solve the problem, cannot replace lexicology essence, can cancel lexicology independence. Grammar is starting with words, phrases, sentences of the research into learning, and it cannot replace lexicology.The important because of its lexicology research object. Words are the most valuable wealth. Word through life, every moment. The word of all aspects of life. Words are the elements of human knowledge. Words are many subjects ~ philosophy, psychology, logic, history and anthropology, ethnology, says bioethicist, aesthetics, literature and art, sociological point of concern. But only lexicology attention is word itself.The object of study, lexicology, western scholars said: lexicology sometimes used to a vocabulary to the overall research (including its history), The psychological meaning of linguistics (such as space relation of language expression) called mental lexical. Lexical differences in learning, the latter is the dictionary compiling dictionaries of science and art. Dictionary so can be regarded as "application" is a branch of vocabulary. "Home" this name lexicology, not too common vocabulary for people who are interested in general also called semantics.