Irtaimisto oli märkää.

Irtaimisto is a collective noun. It refers to a group or body of movable things as one whole, rather than focusing on individual items one by one.

The ending -sto / -istö often forms this kind of “collection” noun in Finnish. So grammatically, irtaimisto behaves like a singular noun, even though its meaning may involve many separate objects.

Here, irtaimisto is in the nominative singular.

It is the subject of the sentence, and its form is the same as the dictionary form. Even though it refers to a collection of things, Finnish still treats it as grammatically singular in this sentence.

Oli is the past tense of olla (to be), in the 3rd person singular.

So:

• on = is
• oli = was

Because irtaimisto is grammatically singular, the verb is singular too: irtaimisto oli.

Because the subject is not grammatically plural.

Even if the meaning involves many items, irtaimisto is still a singular collective noun, so Finnish uses oli, not olivat. If you used a truly plural noun such as huonekalut (the furniture pieces / furnishings), then you would say olivat.

For example:

• Irtaimisto oli märkää.
• Huonekalut olivat märkiä.

Märkää is the partitive singular of märkä (wet).

In Finnish, when the subject is a mass-like, substance-like, or sometimes collective noun, the predicate adjective is often put in the partitive singular. This is the same pattern as in sentences like:

• Vesi on kylmää. = The water is cold.
• Kahvi oli hyvää. = The coffee was good.

Here, irtaimisto is being viewed as a body of “stuff” or contents, so märkää is natural.

Not necessarily.

Here, the partitive is mainly a grammatical choice, not a direct statement that “only some of it” was wet. The sentence can still describe the whole collection in a general way as wet.

So in this sentence, you should not automatically read märkää as only partly wet. It is better to think of it as the normal predicative form used with this kind of noun.

The basic form is märkä.

Here are a few useful forms:

• märkä = wet
• märkää = wet (partitive singular)
• märät = wet (plural nominative)
• märkiä = wet (plural partitive)

So märkää is just an inflected form of the adjective märkä.

You may hear märkä in some contexts, but märkää is the more natural choice when irtaimisto is viewed as a mass-like collection of stuff.

Using märkä would make the noun feel more like one clearly bounded single entity. Using märkää presents it more as a body of contents or movable property in general. In a neutral sentence like this, märkää is the form a learner should expect.

Yes. If you want to talk about individual items more directly, you can use a plural noun.

For example:

• Huonekalut olivat märkiä. = The furniture / furnishings were wet.
• Tavarat olivat märkiä. = The things / belongings were wet.

The original sentence with irtaimisto sounds a bit more formal or collective, like the movable property / contents / furnishings as a whole.

Because Finnish has no articles like a, an, or the.

Whether something is understood as the property, the furnishings, or just property/furnishings depends on the context. So Irtaimisto oli märkää can naturally be translated with the in English even though no separate Finnish word is used for it.