Questions & Answers about Pidän ikkunan auki.
Why is the object ikkunan and not ikkuna?
Because pidän (“I keep”) takes a direct object in the accusative case. In Finnish most singular nouns form the accusative by adding -n, which looks exactly like the genitive. So ikkuna (nominative) → ikkunan (accusative/genitive).
Could I say Pidän ikkunaa auki instead of ikkunan?
You can grammatically, but it changes the nuance. ikkunaa is the partitive, used for indefinite or ongoing quantity. With partitive you’d hint at “some window” or an incomplete action. Here you’re referring to one specific window kept open, so you use the accusative (ikkunan).
What part of speech is auki, and why is it used here?
auki is a resultative adverb (sometimes called a stative complement). It expresses the resulting state “open.” In constructions with verbs like pitää (“keep”), Finnish uses these adverbial complements rather than a full adjective phrase.
Why doesn’t this sentence have a copula like on (“is”)?
Because the main verb pidän already means “I keep.” You attach the state-complement auki directly. If you simply wanted to say “The window is open,” you would use a copula: Ikkuna on auki.