Ákveðinn

óákveðinn is Icelandic an adjective meaning "indefinite" or "undetermined." It is used mainly in linguistic and grammatical contexts to describe noun phrases whose reference is not specified or is non-specific. The term serves as a label in descriptions of grammar rather than a component of everyday speech, where definiteness is typically expressed by the noun’s form rather than a separate word.

In grammar, óákveðinn contrasts with ákveðinn, which means "definite" or "determined." Icelandic marks definiteness primarily through suffixes attached to nouns, and the use of indefiniteness is often understood rather than explicitly indicated by an article. When used attributively, óákveðinn agrees with the noun in gender, number, and case, as in examples such as óákveðinn maður (an indefinite man), óákveðin kona (an indefinite woman), and óákveðið hús (an indefinite house).

Etymology: the word is formed with the negating prefix ó- attached to ákveðinn, itself derived from roots meaning to determine or define. The construction reflects a common pattern in Icelandic for forming the opposite of a stated property.

See also: Icelandic grammar, definiteness and indefiniteness, ákveðinn. References commonly include dictionaries such as Íslenskt orðabók and scholarly works on Icelandic grammar for explanations of indefiniteness as a grammatical category.