eräpäiväin

Eräpäiväin is a historical Finnish form related to the noun eräpäivä, which denotes a due date, deadline, or expiration date for payments or installments. The term appears primarily in older written sources such as contracts, ledgers, and official records, where archaic inflectional patterns were still in use.

Etymology and forms: The base eräpäivä combines erä (batch, installment) with päivä (day). In older Finnish orthography and grammar, the ending -in was used in certain plural or case forms in written records. Consequently, eräpäiväin functions as a historical variant of a plural or plurally inflected form that would today be rendered differently in standard Finnish. The exact grammatical label (for example, plural nominative versus a specialized case form) is tied to older linguistic conventions and may vary in archival texts.

Modern usage: In contemporary Finnish, the standard plural form is eräpäivät, and standard case forms are used according to modern declension rules. Eräpäiväin is now generally encountered only in historical or scholarly contexts, such as studies of old contracts, ledgers, or Finnish orthography. For everyday language, eräpäivät or context-appropriate case forms replace eräpäiväin.

Significance: The term highlights how Finnish legal and financial vocabulary has evolved, retaining the same core concept of a due date while shifting its grammatical forms over time. It is primarily of interest to linguists, historians, and archivists working with older Finnish texts.