In linguistics, a broken plural (or internal plural) is an irregular plural form of a noun or adjective found in the Semitic languages and other Afroasiatic languages such as the Berber languages. Broken plurals are formed by changing the pattern of consonants and vowels inside the singular form. They contrast with sound plurals (or external plurals), which are formed by adding a suffix, but are also formally distinct from phenomena like the Germanic umlaut, a form of vowel mutation used in plural forms in Germanic languages.
There have been a variety of theoretical approaches to understanding these processes and varied attempts to produce systems or rules that can systematize these plural forms. However, the question of the origin of the broken plurals for the languages that exhibit them is not settled, though there are certain probabilities in distributions of specific plural forms in relation to specific singular patterns. As the conversions outgo by far the extent of mutations caused by the Germanic umlaut that is evidenced to be caused by inflectional suffixes, the sheer multiplicity of shapes corresponds to multiplex attempts at historical explanation ranging from proposals of transphonologizations and multiple accentual changes to switches between the categories of collectives, abstracta and plurals or noun class switches.
