kolmannetta
The term "kolmannetta" is the partitive singular form of the Finnish word "kolmas," meaning "third." In Finnish grammar, the partitive case is used in various contexts, including to indicate an indefinite quantity, a part of something, or an incomplete action. Therefore, "kolmannetta" specifically refers to "the third one" or "a third of something" when the noun it modifies is in the partitive case.
For example, if one is talking about a third of a larger group or a third of