This declension (case) indicates a change in state of a noun, with the general sense of "becoming X" or "change to X".

In the Finnish language, this is the counterpart of the Essive case, with the basic meaning of a change of state. It is also used for expressing "in (a language)" and "considering it's a (status)". Its ending is -ksi. Examples:

• pitkä "long", venyi pitkäksi "stretched long"
• englanti "English", englanniksi "in English"
• pentu "cub", Se on pennuksi iso "Considering it's a cub, it is big"