15. Metalingual function: when language is used to talk about and study language itself language is performing metalingual function.
16. General linguistics: the language of language as a whole is often called general linguistics.
17. synchronic linguistics: the descripition of a language at some point in time is a synchronic study, also called synchronic linguistics.
18. Diachronic linguistics: the description of a language as it changes through time is a diachronic study, also called diachronice linguistics.
19. Langue: refers to the abstract linguistic system shared by all the members of a speech community.
20. Parole: refers to the realization of langue in actual use. 21. competence: refers to the ideal user’s knowledge of the rules of his language.
22. performace: refers to the actual realization of the ideal user’s knowledge of the rules of his language in linguistic communication.
23. etic: refers to the linguistic units containing “-etic”, for example: phonetic, morphetic, which are used to describe linguistic facts in detail without distinctive features, are first
used to describe sounds.
24. emic: refers to the linguistic units containing “-emic”, for instance, phonemic, morphemic, which are used to describe abstract linguistic rules with distinctive features, are first used to describe phonemes.
25. phonetics: it is the branch of linguistics which studies the characteristics of speech sounds and provides methods for their description , classification and transcription.
26: phonology: it is the branch of linguistics which studies how sounds are put together and used to convey meaning in communication.
27．Morphology:it is the branch of linguistics which studies how sounds are put together and used to convey meaning in communication.
28. syntax: the words combination is rule-governed, the study of these rules is called syntax as a major branch of linguistics. 29. semantics: the study of meaning of language is known as semantics.
30. pragmatics: the branch of linguistics which studies the meaning in the contex of use is called pragmatics.
31. Psycholinguistics: it is the interdisciplinary study which examines the relationship between language and human brain.
32. sociolinguistics: it is the interdisciplinary study of the relationship between language use and the structure of soceity. 33. anthropological linguistics: it is the investigation that used the theories and methods of anthropology to study language variation and language use in relation to human cultural patterns and beliefs.
34. computational linguistics: as a branch of communication engineering, it is the use of computers and computer techniques to further linguistic research and specific problem solving. 35. Neurolinguistics: it is a branch of linguistics concerned in principle with the physical representation of language or linguistic processes in the brain.
36. linguistic potential: Halliday thinks that with language, there is a wide range of things a speaker can do in the culture he is in. the set of possibility for “doing” is termed linguistic potential from a functional language’s view.
37. actual linguistic behavior: what a speaker actually says on a particular occasion to a particular individual is what he has selected from the many possible things he could have said. This actual selection of things from what one could have said is termed actual linguistic behavior.