Deponency refers to mismatches between morphological form and syntactic function (or “meaning”), such that a given morphological exponent appears in a syntactic environment that is unexpected from the point of view of its canonical (“normal” or “expected”) function. This phenomenon takes its name from Latin, where certain morphologically “passive” verbs appear in syntactically active contexts (for example, hort-or ‘I encourage’, with the same ending as passive am-or ‘I am loved’), but it occurs in other languages as well. Moreover, the term has been extended to include mismatches in other domains, such as number mismatches in nominal morphology or tense mismatches on verbs (e.g., in the Germanic preterite-presents). Theoretical treatments of deponency vary from seeking a unified (and uniform) account of all observed mismatches to arguing that the wide range of cross-linguistically attested form-function mismatches does not form a natural class and does not require explanatory devices specific to the domain of morphology. It has also been argued that some apparent mismatches are “spurious” and have been misanalyzed. Nevertheless, it is generally agreed across frameworks that however such “morphological mismatches” are to be analyzed, deponency has potential ramifications for theories of the syntax-morphology interface and (depending on one’s theoretical approach) the structure of the lexicon.