Pimeällä pysyn kotona, koska katu on liukas.

In the dark I stay at home, because the street is slippery.

Breakdown of Pimeällä pysyn kotona, koska katu on liukas.

• minä: I
• olla: to be
• kotona: at home
• koska: because
• katu: the street
• liukas: slippery
• pysyä: to stay
• pimeällä: in the dark

Questions & Answers about Pimeällä pysyn kotona, koska katu on liukas.

What does pimeällä literally mean, and what case is it?

Pimeä means dark. The form pimeällä is the adessive case (ending -lla/-llä), which usually means on / at something.

Literally, pimeällä is something like “at (the) dark”, but in idiomatic Finnish it works as a time expression:

• pimeällä = when it’s dark / in the dark
  Compare:
• päivällä = in the daytime
• yöllä = at night

So Pimeällä pysyn kotona is really “When it’s dark, I stay at home.”

Why is there no noun after pimeällä? Could you say pimeällä ajalla instead?

Finnish often lets adjectives stand alone as nouns, especially in expressions like this. Here:

• pimeä (dark) → pimeällä works like “in the darkness / when it’s dark”.

You could say pimeällä ajalla (“in the dark time”), but:

• it sounds less natural in this context
• it’s more typical in something like pimeänä vuodenaikana (“in the dark season”) where you specify the time more clearly.

Native speakers normally just say pimeällä here, without any extra noun.

Could you say Pimeässä pysyn kotona instead of Pimeällä pysyn kotona? What’s the difference?

Pimeässä pysyn kotona is grammatically correct but sounds less natural on its own.

• pimeällä (adessive) is the normal choice for time: “when it’s dark”.
• pimeässä (inessive, “in the dark”) focuses more on being inside darkness / a dark space, so it usually needs a clearer context:
  • Seison pimeässä huoneessa. = I’m standing in a dark room.
  • Kuljen pimeässä metsässä. = I walk in a dark forest.

So:

• Pimeällä pysyn kotona = When it’s dark (outside, generally), I stay at home. ✅ very natural
• Pimeässä pysyn kotona = In the dark I stay at home. ✔ grammatical, but feels a bit vague and unusual without more context.

Why is pysyn used instead of olen or jään? What’s the nuance?

All three are related but not identical:

• pysyä = to stay / remain
  
  • pysyn kotona = I stay (I remain) at home.
• olla = to be
  
  • olen kotona = I am at home (just a neutral statement of location).
• jäädä = to stay / remain (instead of going), often focusing on the moment of deciding not to leave
  
  • jään kotiin = I (will) stay home / I’m staying at home (I’m not going out).

In this sentence, pysyn kotona emphasizes an ongoing habit or rule:

• Pimeällä pysyn kotona ≈ “When it’s dark, I stay at home” (I don’t go out; that’s my practice).
  Using olen kotona would sound more like you’re simply describing your location, not the idea of staying there.

Why is kotona used here and not kotiin or kotoa?

These are three different local forms of koti (home), and they answer different “where?” questions:

• kotona = at home (location, “where?”)
  
  • Pysyn kotona. = I stay at home.
• kotiin = to home (movement towards, “where to?”)
  
  • Menen kotiin. = I’m going home.
• kotoa = from home (movement away, “from where?”)
  
  • Lähden kotoa. = I leave home.

In Pimeällä pysyn kotona, the idea is “I stay at home (I remain there)”, so kotona (location) is the correct form.

Why is there a comma before koska? Is it always required?

In Finnish, a subordinate clause introduced by koska (because) is normally separated from the main clause by a comma:

• Pimeällä pysyn kotona, koska katu on liukas.
  
  • main clause: Pimeällä pysyn kotona
  • subordinate clause: koska katu on liukas

Yes, this comma is standard and expected in written Finnish.
Whether the because-clause comes first or second, you put a comma between the two clauses:

• Koska katu on liukas, pysyn kotona.
• Pysyn kotona, koska katu on liukas.

Does koska only mean because, or can it also mean when?

Koska has two main uses:

1. “because” (as in this sentence):

   • Pysyn kotona, koska katu on liukas.
     = I stay at home because the street is slippery.

2. “when” in questions about time:

   • Koska tulet? = When are you coming?

In subordinate clauses, koska is usually understood as because. When it means when as a conjunction, Finnish more typically uses kun:

• Kun on pimeää, pysyn kotona. = When it is dark, I stay at home.

So here koska clearly means because.

Why doesn’t Finnish say “the street” in katu on liukas? How do I know if it’s “the” or “a” street?

Finnish has no articles (no a/an, no the). The bare noun katu can correspond to:

• a street
• the street
• streets in general

You infer the exact meaning from context:

• In this sentence, the natural English translation is “the street is slippery”, probably meaning the street outside where I live / the one I’d walk on.
• If context were more general, katu on liukas could also be translated “a street is slippery” or “the street (as a type of place) is slippery”.

Finnish often relies on shared knowledge rather than marking definiteness grammatically.

Why are both katu and liukas in the basic form (nominative) in katu on liukas?

In Finnish, when you say X is Y and Y is an adjective, the pattern is:

• subject (nominative) + olla + adjective (nominative)

Here:

• katu (street) = subject, nominative
• on = 3rd person singular of olla (to be)
• liukas (slippery) = adjective in nominative, describing katu

So katu on liukas literally mirrors English “the street is slippery”, except that Finnish doesn’t have an article.

Could you also say katu on liukasta? What’s the difference from katu on liukas?

Yes, katu on liukasta is possible, but there is a nuance.

• katu on liukas (adjective in nominative) states a clear quality:
  
  • “The street is slippery.” (a straightforward description)
• katu on liukasta (adjective in the partitive) can suggest:
  • the slipperiness is seen more as a substance/amount (“there is slipperiness”), or
  • a more vague or partial quality (“it’s kind of slippery / there’s slippery stuff on it”).

In everyday speech, many people alternate between the two without strong awareness of the nuance, but:

• katu on liukas is the neutral, textbook version for this sentence.
• katu on liukasta can sound a bit more colloquial / descriptive of the current condition.

In English we say “When it’s dark, I stay at home…” with it as a dummy subject. Why doesn’t Finnish use a word for “it” in Pimeällä pysyn kotona?

Finnish doesn’t need a dummy subject like English it in weather and time expressions. Instead, it often uses:

• a time adverbial alone:
  
  • Pimeällä pysyn kotona. ≈ “When it’s dark, I stay at home.”
• or a clause with on and an adjective:
  
  • Kun on pimeää, pysyn kotona. = When it is dark, I stay at home.

Compare other expressions:

• Sataa. = It is raining. (no it)
• On kylmä. = It is cold.

So pimeällä itself carries the idea “when it is dark”, without any extra pronoun.

Could the word order be Pysyn kotona pimeällä, koska katu on liukas? Does that change the meaning?

Yes, that word order is correct:

• Pysyn kotona pimeällä, koska katu on liukas.

In Finnish, adverbials like pimeällä can move quite freely:

• Pimeällä pysyn kotona, koska katu on liukas.
• Pysyn kotona pimeällä, koska katu on liukas.

Both mean the same thing. The difference is only in emphasis / rhythm:

• Starting with Pimeällä slightly highlights the time condition (“As for when it’s dark, then I stay at home…”).
• Putting pimeällä later can make pysyn kotona feel more central (“I stay at home (and specifically) when it’s dark…”).

Semantically, though, they are equivalent in normal contexts.