alterum

Alterum is a Latin word that functions as both an adjective and a pronoun, meaning “the other” or “the second of two.” It derives from the base adjective alter and occurs in classical Latin to distinguish one item from another in a paired context. In ordinary prose it can modify a noun (as an attributive adjective) or stand alone as a substantive pronoun meaning “the other one.”

Grammatically, alterum appears in the standard pattern of a first/second declension adjective. In the singular it is used as masculine accusative and neuter nominative/accusative in the form alterum; the feminine nominative is altera. The remaining singular forms include alterius (genitive), alteri (dative), and altero (ablative). The forms for plural and other cases follow the same declensional behavior, with the exact endings varying by gender and number. The form alterum is also encountered in phrases such as ex altero and alterum ex duobus, meaning “from the other (one)” or “the other of two,” respectively.

Alterum is commonly contrasted with alius, another Latin term for “another” or “a different one.” While alius often signals a non-identical alternative in a broader sense, alter emphasizes the distinction between two specific items or options.

In use, alterum appears throughout classical Latin literature and remains a standard element of Latin grammar and style. It is typically taught as part of the vocabulary distinguishing two-way contrasts and paired references. See also alter, alius.