In linguistics, syncretism exists when functionally distinct occurrences of a single lexeme, morph or phone are identical in form. The term arose in historical linguistics, referring to the convergence of morphological forms within inflectional paradigms. In such cases, a former distinction has been 'syncretized'. The term syncretism is often used when a fairly regular pattern can be obserbed across a paradigm.
Syncretism can arise through either phonological or morphological change. In the case of phonological change, originally distinct forms change to be pronounced identically, so that their distinctness is lost. Such change can often be observed in the modern German verb paradigm: the infinitive nehmen 'to take' comes from Old High German neman, the first person plural declension nehmen comes from nem?m, and the third person plural nehmen comes from nemant. This is also an example of syncretism manifested in lexemes.
|Old High German||-->||Modern German|
In the case of morphological change, one form stops being used and is replaced by the other. This change can be exemplified by the syncretism in Latin's third-declension nouns, whose nouns take the same form in nominative and vocative cases.
In English, syncretism led to the loss of case marking and the stabilization of word order. For example, the nominative and accusative forms of you are the same, whereas he/him, she/her, etc., have different forms depending on grammatical case.
Another English example for syncretism can be observed in most English verb paradigms: there is no morphological distinction between the past participle and the passive participle, and, often, the past tense.
|past tense||past participle||passive particple|
The syncretism observed here differs from the lexcial syncretism observed in English personal pronouns inasmuch that the syncretism manifests itself in the suffix or stem change in the case of walked and won, respectively.
In Latin, the nominative and vocative of third-declension nouns have the same form (e.g. r?x 'king' is both nominative and vocative singular), distributing syncretism in case marking. Another observation is the distinction between dative and ablative, which is present in singular (e.g., puellae 'girl-DAT.SG' and puella 'girl-ABL.SG'), but not anymore in plural (e.g., puellis 'girl-DAT.PL/girl-ABL.PL'.
Similarly, in German, the infinitive, first person plural present, and third person plural present of almost all verbs are identical in form (e.g. nehmen "to take", wir nehmen "we take", sie nehmen "they take").