In linguistics, word formation is the creation of a new word. Word formation is sometimes contrasted with semantic change, which is a change in a single word's meaning. The line between word formation and semantic change is sometimes a bit blurry; what one person views as a new use of an old word, another person might view as a new word derived from an old one and identical to it in form; seeConversion (linguistics). Word formation can also be contrasted with the formation of idiomatic expressions, though sometimes words can form from multi-word phrases; seeCompound (linguistics) and Incorporation (linguistics).
Conversion (linguistics) (forming a new word from an existing identical one, like forming the verb green from the existing adjective)
Loanword (a word borrowed from another language, like cliché, which comes from French)
Calque (borrowing a word or phrase from another language by literal, word-for-word or root-for-root translation; for example the English phrase to lose face, which is a calque from Chinese)
Phono-semantic matching (matching a foreign word with a phonetically and semantically similar pre-existent native word/root)
Semantic loan (the extension of the meaning of a word to include new, foreign meanings)
Onomatopoeia (the creation of words that imitate natural sounds, like the bird name cuckoo)
Literature
Hadumod Bussmann (1996), Routledge Dictionary of Language and Linguistics, London: Routledge.
Joachim Grzega (2004), Bezeichnungswandel: Wie, Warum, Wozu? Ein Beitrag zur englischen und allgemeinen Onomasiologie, Heidelberg: Winter.
Peter Koch (2002), “Lexical Typology from a Cognitive and Linguistic Point of View”, in D. Alan Cruse et al. (eds), Lexicology: An International Handbook on the Nature and Structure of Words and Vocabularies / Lexikologie: Ein internationales Handbuch zur Natur und Struktur von Wörtern und Wortschätzen, [Handbücher zur Sprach- und Kommunikationswissenschaft 21], Berlin/New York: Walter de Gruyter, vol. 1, pp. 1142-1178.
Ghil'ad Zuckermann (2003). Language Contact and Lexical Enrichment in Israeli Hebrew. Houndmills: Palgrave Macmillan. (Palgrave Studies in Language History and Language Change). ISBN 1-4039-1723-X.