There are various definitions of applied linguistics based on some linguists. The followings are some of them:
a. ‘Applied Linguistics (AL) provides the theoretical and descriptive foundations for the investigation and solution of language-related problems, especially those of language education (first-language, second-language and foreign-language teaching and learning), but also problems of translation and interpretation, lexicography, forensic linguistics and (perhaps) clinical linguistics.’ (Dick Hudson’s online survey of BAAL British Association of Applied Linguistics members)
Retrieved from http://homepage.ntlworld.com/vivian.c/AppliedLinguistics/AppLingDefining.htm on March 20th, 2013.
b. Applied Linguistics itself may be seen as an autonomous, problem-solving disciple, concerned broadly with language (mainly, but not exclusively second language) education and language problems in society’ (Steve McDonough, 2002)
c. Schmitt and Celce-Murcia offer the following definition of Applied Linguistics, (which they place in inverted commas): “‘Applied Linguistics’ is using what we know about (a) language, (b) how it is learned, and (c) how it is used, in order to achieve some purpose or solve some problem in the real world” (Schmitt & Celce-Murcia, 2002, p. 1).
Alan Davies and Catherine Elder, 2004. The Handbook of Applied Linguistics. Blackwell Publishing. E-book retrieved from http://faculty.ksu.edu.sa/76518/Linguistics/books/the%20handbook%20of%20applied%20linguistics.pdf on March 8th 2013
In my opinion, Applied Linguistics is a discipline to solve language problems which can be identified and analyzed in the society especially for the field of language education and second language.
The Scope of Applied Linguistics
Cook recognises that ‘the scope of applied linguistics remains rather vague’.
a. According to Mouton de Gruyter, the scope of applied linguistics includes:
Language Acquisition (L1 and L2), Psycho/Neuro - linguistics, Language Teaching, Sociolinguistics, Humor Studies, Pragmatics, Discourse Analysis/Rhetorics, Text/Processing/Translation, Computational Linguistics – Machine Translation, Corpus Linguistics, Language Control/Dialectology.
Davies, A. 2007. An Introduction to Applied Linguistics. From Practice to Theory. Edinburgh: Edinburgh University Press.
b. According to the International Association of Applied Linguistics, the scope of applied linguistics includes:
Adult Language Learning, Child Language, Communication in the Professions, Contrastive Linguistics and Error Analysis, Discourse Analysis, Educational Technology and Language Learning, Foreign Language Teaching Methodology and Teacher Education, Forensic Linguistics, Immersion Education, Interpreting and Translating, Language and Ecology, Language and Education in Multilingual Settings, Language and Gender, Language and the Media, Language Contact and Language Change, Language for Special Purposes, Language Planning, Learner Autonomy in Language Learning, Lexicography and Lexicology, Literacy, Mother Tongue Education, Psycholinguistics, Rhetoric and Stylistics, Second Language Acquisition, Sign Language.
Seidlhofer, B. 2003. Controversies in Applied Linguistics. United Kingdom: OXFORD University Press.
Beside the above explanation about the scope of applied linguistics, there are some more others:
a. Language and Teaching
This scope covers methods of language teaching. In doing teaching learning activity, linguistic is applied on those methods.
b. Language and Society
The branch in this scope is called sociolinguistics. Sociolinguistic studies about the relationship between the society and language, and explore/solve the problem related to society that affects the language, varieties of language in society, terms of taboos and euphemism, etc.
c. Language Education/Learning
This scope tries to explain about the first language education, additional language education such as second language education and foreign language education. It also help us to know about clinical linguistic and language testing. Clinical linguistic is the study about language disability.
d. Language, Work and Law
The scope of Language, Work and Law explain about communication in the workplace, language planning and forensic linguistic.
e. Language, Information and Effect
It studies the literary stylistics, critical discourse analysis, translation and interpretation, information design, and lexicography.
Mai Mustafa Fouad Ra’fat Ali.(n.d).Applied Linguistic.Retrieved from http://www.scribd.com/doc/58883443/Applied-Linguistics-1-the-Scope-of-Applied-Linguistics