Descriptive:
Linguistics. Describing the structure of a language at a given time,
avoiding comparisons with other languages or other historical phases, and
free from social valuations; as in descriptive grammar, linguistics, etc.
(Opp. normative, prescriptive, historical; cf. SYNCHRONIC a.)
http://dictionary.oed.com/cgi/entry/50187791?single=1&query_type=word&queryword=prescriptive&first=1&max_to_show=10
Descriptive Grammar:
A descriptive grammar looks at the way a language is actually used by its
speakers and then attempts to analyse it and formulate rules about the structure.
Descriptive grammar does not deal with what is good or bad language use;
forms and structures that might not be used by speakers of Standard English
would be regarded as valid and included. It is a grammar based on the way
a language actually is and not how some think it should be.
http://www.english-for-students.com/Descriptive-and-Prescriptive.html
Diachronic:
Linguistics. [tr. F. diachronique (F. de Saussure a 1913, in Cours
de linguistique générale (1916) iii. 120).] Pertaining to or
designating a method of linguistic study concerned with the historical development
of a language; historical, as opposed to descriptive or synchronic. Also
transf., in Anthropology, etc. Hence dia chronically adv.; di achrony.
http://dictionary.oed.com/cgi/entry/50063005?single=1&query_type=word&queryword=diachronic&first=1&max_to_show=10
Dialect:
1. Manner of speaking, language, speech; esp. a manner of speech peculiar
to, or characteristic of, a particular person or class; phraseology, idiom.
2. a. One of the subordinate forms or varieties of
a language arising from local peculiarities of vocabulary, pronunciation,
and idiom. (In relation to modern languages usually spec. A variety of speech
differing from the standard or literary ‘language’; a provincial method of
speech, as in ‘speakers of dialect’.) Also in a wider sense applied to a
particular language in its relation to the family of languages to which it
belongs.
b. attrib., as dialect speech, speaker,
poems, specimens; dialect atlas, geography: see quots. 1933; hence dialect-geographer,
dialect-geographical adj.
http://dictionary.oed.com/cgi/entry/50063104?query_type=word&queryword=dialect&first=1&max_to_show=10&sort_type=alpha&result_place=1&search_id=ehQJ-L4zKsT-5039&hilite=50063104
Lexical diffusion:
Chen and Wang (1975): “a phonological rule gradually extends its scope
of operation to a larger and larger portion of the lexicon, until all relevant
items have been transformed by the process.”
http://209.85.129.132/search?q=cache:nIEOKkoa_-wJ:www.stanford.edu/dept/linguistics/linginst/nsf-workshop/PhilipsSlides.ppt+lexical+diffusion&cd=2&hl=es&ct=clnk&gl=es
Neogrammarian:
n. A linguist holding the view that phonetic changes operate without
exception.
http://dictionary.oed.com/cgi/entry/00322902?single=1&query_type=word&queryword=neogrammarian&first=1&max_to_show=10
Normative:
adj. That constitutes or serves as a norm or standard; implying or
derived from a norm; prescriptive.
n. A normative standard, a norm.
SPECIAL USES
normative grammar n. a system of grammatical rules set up as a standard
to which language in use must conform; (also) a work setting out such rules.
http://dictionary.oed.com/cgi/entry/00327077?query_type=word&queryword=prescriptive&first=1&max_to_show=10&single=1&sort_type=alpha
Prescriptive:
That prescribes or directs; giving definite, precise directions or
instructions. In later use, in Linguistics: that lays down rules of usage.
In Linguistics, opposed to descriptive (see DESCRIPTIVE adj. 3b). See
also normative grammar n. at NORMATIVE adj. and n. Special uses.
http://dictionary.oed.com/cgi/entry/50187791?single=1&query_type=word&queryword=prescriptive&first=1&max_to_show=10
Prescriptive Grammar:
A prescriptive grammar lays out rules about the structure of a language.
Unlike a descriptive grammar it deals with what the grammarian believes to
be right and wrong, good or bad language use; not following the rules will
generate incorrect language.
http://www.english-for-students.com/Descriptive-and-Prescriptive.html
Register:
Linguistics. A variety of a language or a level of usage, spec. one
regarded in terms of degree of formality and choice of vocabulary, pronunciation,
and (when written) punctuation, and related to or determined by the social
role of the user and appropriate to a particular need or context.
http://dictionary.oed.com/cgi/entry/50201234?query_type=word&queryword=register&first=1&max_to_show=10&sort_type=alpha&result_place=1&search_id=WB8t-cFREEQ-7202&hilite=50201234
Synchronic:
Linguistics. [tr. F. synchronique (F. de Saussure a 1913, in Cours
de linguistique générale (1916) iii. 117).] Pertaining to or
designating a method of linguistic study concerned with the state of a language
at one time, past or present; descriptive, as opposed to historical or diachronic.
Also transf. in Anthropology, etc.
http://dictionary.oed.com/cgi/entry/50245273?single=1&query_type=word&queryword=synchronic&first=1&max_to_show=10