Deflexion is a linguistic process related to inflectional languages. All members of the Indo-European language family belong to this kind of languages and are subject to some degree of deflexional change. The process is typified by the degeneration of the inflectional structure of a language. This phenomenon has been especially strong in Western European languages, such as French, English and Afrikaans.
Deflexion typically involves the loss of some inflectional affixes, notably affecting word endings (markers) which indicate noun cases, verbal tenses and noun classes. This is part of a process of gradual decline of the inflectional morphemes, defined as atomic semantic units bound to abstract word units (lexemes). Complete loss of the original subset of affixes combined with a development towards allomorphy and new morphology is associated in particular with creolization, i.e. the formation of pidgins and creole languages.
Deflexion is a common feature of the history of many Indo-European languages. According to the Language Contact Hypothesis for Deflexion, supported by the comparison between Germanic languages, for instance, Icelandic and Afrikaans, this process is attributed to language contact. Specifically, the phenomenon occurs in the presence of large, influential groups of speakers that have acquired the leading idiom as a second language (L2 acquisition), thus by nature is limited to economical trade-offs widely considered as acceptable. Though gradual, English experienced a dramatic change from Old English being a moderately inflected language using a complex case system, to Modern English, considered a weakly inflected language or even analytic. Important deflexion changes first arrived in the English language with the North Sea Germanic (Ingvaeonic) shifts, shared by Frisian and Low German dialects, such as merging accusative and dative cases into an objective case. Viking invasions and the subsequent Norman conquest accelerated the process. The importance of deflexion in the formative stage of a language can be illustrated by modern Dutch, where deflexion accounts for the overwhelming majority of linguistic changes in the last thousand years or more. Afrikaans virtually originated from Dutch by deflexion. French is another example of a language where deflexion has been exceptionally strong.
According to the unidirectionality hypothesis, deflexion should be subject to a semantically driven one-way cline of grammaticality. However, exceptions to the gradual diachronic process have been observed where the deflexion process diminished or came to a halt, or where inflexional case marking was occasionally reinforced.
Alternative view 
Deflectional change as a linguistic process has been denied by those that question the existence of a rich inflectional system in proto-Germanic. A variety of propositions have been invoked in support of the allegation that Germanic languages originally lacked declinations:
- The alleged overall poverty of Germanic languages in grammatical categories such as case, gender, number, tense and mood;
- The "frozen" status of many modern German proverbs and idioms involving words whose former indications of case, gender and number have worn off in non-"frozen" contexts (e.g., retention of the dative case ending -e in zu Hause ["at home"] and nach Hause ["home(ward)"]); and
- A mistaken statement that Old French "emerged without case and number" from the confrontation between Vulgar Latin and the Germanic languages of the conquering Franks
See also 
Notes and references 
- Encyclopedia of Language and Linguistics, Elsevier, 2004, Pidgins affix dropping (6:3187)
- Morphology in pidgins and Creoles, Ingo Plag, University of Siegen, Version of June 28, 2004, 
- What are the factors that cause deflection? In order to answer this question, the Meertens Institute (KNAW) and the Amsterdam Center for Language and Communication (UvA) have started a research-program called Variation in Inflection, or simply Variflex . “The loss of inflectional distinctions and the language contact hypothesis have often been discussed in the literature, but have never been the subject of extensive and integrated research. This is probably due to the need for a complex, multidisciplinary approach. Such a research programme would have to combine theoretical linguistics, diachronic linguistics, dialectology, first language acquisition and second language acquisition.”(The original Variflex proposal)
- The Development of Case in Germanic - Jóhanna Barðdal, University of Bergen 
- Weerman, F. (1993), The diachronic consequences of first and second language acquisition
- Hopper, Paul J. and Elizabeth Closs Traugott: Grammaticalization, 1993, Cambridge University Press.
-  Indo-European Vocabulary in Old Chinese: A New Thesis on the Emergence of Chinese Language and Civilization in the Late Neolithic Age - Tsung-tung Chang, SINO-PLATONIC PAPERS Number 7 (January, 1988)