ajanjaksoin

Ajanjaksoin is a Finnish noun form that appears to be derived from ajanjakso, meaning a time period or span of time. In contemporary standard Finnish, the most common terms are ajanjakso (singular) and ajanjaksot (plural); the form ajanjaksoin is not widely used in everyday language. When Finnish nouns like this are inflected, common related forms include the genitive ajanjakson, the genitive plural ajanjaksojen, the inessive plural ajanjaksoissa, and the illative plural ajanjaksoihin. The specific ending -in in ajanjaksoin is not typical of standard modern usage and is generally found only in dialectal, historical, or pedagogical contexts used to illustrate inflectional patterns rather than as a regular vocabulary item.

Etymologically, ajanjaksoin is built from ajan and jakso, the components of ajanjakso, with a suffix that signals a particular inflectional form in some descriptions. Because standard Finnish tends to favor the more common inflected forms mentioned above, ajanjaksoin is regarded as an atypical or largely archaic variant rather than a productive everyday form. In practical writing and speech, speakers would typically substitute ajanjakso, ajanjaksot, or the standard inflected forms appropriate to the intended case.