Coinage: refers so the creating of words that are completely new and not derived in any way from other words.
Borrowing: occurs when words are taken from other languages.
Affixing: is the most common source of new words. its involved adding prefixes or suffixes to existing words to form new words.
Compounding =: occurs when words are combined to form a new, larger words or expression. e.g. blackbird and laptop.
Blends: are similar to compunding, except that only parts of each word are joined together. e.g. smog for smoke and fog.
Conversion: occurs when the word class of an existing words changes, creating a new use for the word.
Abbreviation: a new word is formed by shortening an existing word in some way. e.g. advert from advertisement
Back-formation: a particular kind of shortening in which a word of one type (usually a noun) is shortened to form a word of another type (usually a verb). e.g burgle from burgular
Acronyms: words formed from the initial letters of existing words, a process virtialy unknown before the 20th century.
Words from names: some words derive from the names of people or places. e.g. sandwhich is names after the fourth earl of sandwhich.
Archaisms: words and phrases that become obsolete are known as archaisms. words that fall out of use. e.g. shakespear's plays contain loads of archaisms enow for enough.
Broadening: this occurs when the meaning of a word broadens, so that i retains its old meaning but takes on an added meaning as well.
Narrowing: the opposite of broadening. here a word becomes more specific in its meaning.
Amelioration: this occurs when the change gives the word a meaning that is more pleasant or more positive.
Pejoration: this occurs when the change in meaning is the opposite direction to amelioration, becomming less favourable.
Weakening: this refers to words losing over time some of their original force or strength.
Metaphor: words often acquire new meanins because they begin to be used metaphorically.
Idioms: are always formed from previously existing words. e.g. i'm in the doghouse
Euphemisms: is a mild or inoffesnsive way of describing something distasteful or unpleasent.
Political correctness: in modern Egnlish, some semantic change has arisen from the desire for political correctness. there has been a drive to replace words and expressions that are considered offensive or demeaning to disadvantaged or minority groups,
Aitchison 1991 has identified four stages to phonological changes
stage one: the speech of a particular social group differs in some ways from the usual pronunciation of the area in which they live.
stage two: a second social group begins - possibly unconsciously - to imitate the speech of the first group.
stage three: the new pronunciation becomes established among the second group - it is now part of their usual accent.
stage four: a third social group now begins to model itself on the second group, and the process repeats itself.