Pidän ikkunan auki.

I keep the window open.

Breakdown of Pidän ikkunan auki.

• minä: I
• ikkuna: the window
• auki: open
• pitää: to keep

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.

How do I make the negative, “I don’t keep the window open”?

Use the negative form of pitää and switch the object to partitive:
En pidä ikkunaa auki.
In Finnish negative sentences the object usually becomes partitive.

How do I say “I kept the window open” (past tense)?

Change pidän to the past tense pidin:
Pidin ikkunan auki.

Can I use an adjective instead of auki, e.g. avoin or avoinna?

You cannot say Pidän ikkunan avoin directly, but you have two options:

• Pidän ikkunan avoinna (using the instructive -na/-nä form of avoin).
• More simply, auki is far more common in speech. Both mean “I keep the window open,” but auki is the usual colloquial choice.