Old Norse morphology

Old Norse has three categories of verb (strong, weak, & present-preterite) and two categories of noun (strong, weak). Conjugation and declension are carried out by a mix of inflection and two nonconcatenative morphological processes: umlaut, a backness-based alteration to the root vowel; and ablaut, a replacement of the root vowel, in verbs.

Nouns, adjectives and pronouns are declined in four grammatical cases – nominative, accusative, genitive and dative, in singular and plural. Some pronouns (first and second person) have dual number in addition to singular and plural. The nouns have three grammatical genders – masculine, feminine or neuter - and adjectives and pronouns are declined to match the gender of nouns. The genitive is used partitively, and quite often in compounds and kennings (e.g.: Urðarbrunnr, the well of Urðr; Lokasenna, the gibing of Loki). Most declensions (of nouns and pronouns) use -a as a regular genitive plural ending, and all declensions use -um as their dative plural ending.

All neuter words have identical nominative and accusative forms, and all feminine words have identical nominative and accusative plurals.

The gender of some words' plurals does not agree with that of their singulars, such as lim and mund.

Conditioned sound changes can cause some forms of a word to mismatch, or match in some words but not others. When speakers can't determine these conditions, but the effects remain, they are re-analyzed by speakers as rules for changing sounds during inflection, the morphophonology of the language. In this way, the history of a language affects its speakers.

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