Peräkkäisten

Peräkkäisten is the genitive plural form of the Finnish adjective peräkkäinen, which means consecutive or sequential. It is used to describe a noun in the genitive plural, for example in phrases like peräkkäisten numeroiden summa, “the sum of consecutive numbers.” The corresponding nominative plural form is peräkkäiset.

In Finnish, adjectives agree with the nouns they modify in case and number. When the noun is in genitive plural, the adjective takes the genitive plural form, which for peräkkäinen is peräkkäisten. This form is common in mathematical, statistical, and temporal contexts where a set of items follows one another in order.

Etymology comes from perä, meaning behind or after, combined with -kainen, a suffix creating adjectives meaning “characteristic of” or “related to.” Thus peräkkäinen conveys order and succession, and peräkkäisten attaches to nouns to specify that the described items are in a sequence rather than scattered.

Usage notes: peräkkäisten is most often found in formal or written Finnish, especially in technical texts. It can modify a wide range of nouns, such as peräkkäisten päivien tapahtumat (events of consecutive days) or peräkkäisten arvojen järjestys (the order of consecutive values). In everyday language, speakers may use peräkkäiset or other synonyms like järjestäytyneet to convey similar ideas, but peräkkäisten remains the standard grammatical form when the noun is in genitive plural.