sisääntöön
Sisääntöön is a Finnish word that translates to "into the content" or "into the input" in English. It is a grammatical case ending, the illative, used to indicate movement or direction towards the inside of something. The illative case in Finnish is formed by adding the suffix -Vn, where V is a vowel that harmonizes with the preceding vowel of the word. For example, talo (house) becomes taloon (into the house), and kirja (book) becomes kirjaan (into the book).
The illative case is not limited to physical movement. It can also express abstract concepts such as