Þessi trefill passar vel við húfuna.

This scarf goes well with the hat.

Breakdown of Þessi trefill passar vel við húfuna.

• vel: well
• þessi: this
• trefillinn: the scarf
• húfan: the hat

Questions & Answers about Þessi trefill passar vel við húfuna.

Why is the sentence Þessi trefill passar vel við húfuna and not Þetta trefill?

Because trefill is a masculine singular noun, and the demonstrative þessi has to agree with it in gender, number, and case.

Here:

• þessi = this for a masculine/feminine noun in the nominative singular
• trefill = a masculine singular noun
• the whole phrase Þessi trefill means this scarf

Compare:

• þessi trefill = this scarf
• þetta is used with neuter nouns, not with trefill

So the form þessi is chosen because it matches trefill.

What case is trefill in here?

Trefill is in the nominative singular.

It is the subject of the sentence — the thing doing the action of matching / going well with something.

So:

• Þessi trefill = subject
• passar = verb
• við húfuna = prepositional phrase, with the hat

In Icelandic, subjects are very often in the nominative case, just like here.

What does passar við mean here?