Learn Hardcore Icelandic: Umferðin er meiri í dag en í gær. - The traffic is heavier today than yesterday.

Breakdown of Umferðin er meiri í dag en í gær.

What does Umferðin mean, and what does the ending -in do?

Umferð means traffic. The ending -in is the definite article attached to the noun, so umferðin means the traffic.

This is very common in Icelandic: instead of a separate word for the, the article is often added to the end of the noun.

Is umferð singular or plural here?

It is singular. Umferð is a singular mass noun, like English traffic.

So even though traffic involves many cars, the grammar treats it as one singular idea:

That is why the verb is er = is, not a plural verb.

Why is it meiri and not meira?

Because meiri has to match umferðin grammatically.

The noun umferð is feminine singular, and the comparative adjective agrees with it. So here Icelandic uses meiri.

The basic comparison is:

Meira is the neuter singular form, and it is also often used adverbially, so it does not fit this noun here.