Lasi on puolillaan vettä.

The glass is half full of water.

Breakdown of Lasi on puolillaan vettä.

• olla: to be
• vesi: the water
• lasi: the glass
• puolillaan: half full

Questions & Answers about Lasi on puolillaan vettä.

Why is vettä in the partitive case in Lasi on puolillaan vettä?

Vettä is the partitive form of vesi. In Finnish, the partitive marks an incomplete or indefinite quantity. Since the glass is only half full (not completely full), the water remains a partial amount—hence vettä, not vesi (nominative) or vedet (plural).

What part of speech is puolillaan? Is it an adjective, adverb…?

Puolillaan is not a simple adjective or adverb but a noun form (from puolet, “halves”) in the adessive plural, carrying a 3rd-person possessive suffix. Functionally it works like an adverbial phrase meaning “in halves” or “halfway.”

Can you break down puolillaan morphologically?

Yes:

1. Start from puolet (“halves,” nominative plural).
2. Adessive plural (location “on/by halves”): puolilla.
3. Add 3rd-person singular possessive -nsa (“its”): puolilla + nsa → puolillansa.
4. Assimilation ns → nn yields puolillaan.
   Literally it means “on its halves.”

Why does puolillaan have a possessive suffix? What does it refer to?

The suffix -nsa refers back to the subject lasi (“the glass”). So puolillaan literally means “on its halves,” i.e. the glass has water up to its own halfway point.

Is there another way to say “the glass is half full of water” in Finnish?

Yes. A very common alternative is: – Lasi on puoliksi täynnä vettä.
Here puoliksi is an adverb (“half-wise”), täynnä is the adjectival form of täysi (“full”), and vettä stays in the partitive.

Can I drop vettä and just say Lasi on puolillaan?

You can, but only if context makes it clear what the glass contains. Lasi on puolillaan on its own means “The glass is half full.” If you need to specify what it’s half full of, add vettä (or another liquid).

Can I use this structure with other containers or liquids?

Absolutely. You can replace lasi and vettä freely. For example:
– Pullo on puolillaan maitoa. (“The bottle is half full of milk.”)
– Ämpäri on puolillaan vettä. (“The bucket is half full of water.””)