þriðja

Þriðja is the Icelandic ordinal numeral meaning “third.” It is used to indicate the third item in a sequence and typically precedes the noun it modifies. In Icelandic, ordinal adjectives agree with the noun’s gender; the masculine singular form is þriðji, while the feminine and neuter singular form is þriðja. For example, Þriðji dagur mánaðarins refers to the third day of the month, and Þriðja bók means the third book. When the noun is definite, the ordinal form shares in the noun’s definiteness and appears as part of the noun phrase (e.g., þriðji dagurinn, þriðja bókin).

Grammatical notes: as with other Icelandic adjectives, the form of þriðja changes to align with the noun’s gender and definiteness. The word is commonly used in counting sequences, dates, and enumerating items, and it is also found in fixed phrases and titles where order is important.

Etymology and cognates: þriðja derives from Old Norse and is cognate with related North Germanic forms such as Swedish tredje, Norwegian tredje, and Danish tredje. These in turn trace back to a Proto-Germanic root meaning “third.” The Icelandic form reflects typical North Germanic patterns of gendered adjective endings.

See also: Icelandic numerals, ordinal numbers, adjective declension in Icelandic, related numbers in North Germanic languages.