Hún finnur hitamælinn í baðherberginu og mælir hitann sinn.

Finnur is the 3rd person singular present tense of finna (to find).

So:

• ég finn = I find
• þú finnur = you find
• hún finnur = she finds

In this sentence, hún finnur means she finds.

Because hitamælinn is a definite direct object.

• hitamælir = thermometer / a thermometer (dictionary form)
• hitamælinn = the thermometer

Icelandic usually adds the to the end of the noun instead of using a separate word.

Also, the noun is the object of finnur, so it appears in the form required there. That is why learners often see a different ending from the dictionary form.

In Icelandic, the definite article is usually attached to the noun as a suffix.

For example:

• hitamælinn = the thermometer
• baðherberginu = the bathroom
• hitann = the temperature

So instead of a separate word like English the, Icelandic often builds definiteness into the noun itself.

Here í means in, and baðherberginu means the bathroom.

The important grammar point is that í can take different cases depending on meaning:

• location = usually dative
• movement into something = usually accusative

In this sentence, she is finding the thermometer in the bathroom—that is a location, not motion—so Icelandic uses the location form:

• í baðherberginu = in the bathroom

Compare:

• í baðherberginu = in the bathroom
• í baðherbergið = into the bathroom

Yes, and that can be confusing at first.

In mælir hitann sinn, mælir is a verb:

• mæla = to measure
• mælir = measures

But inside hitamælinn, the element -mælir is part of a noun:

• hitamælir = thermometer

So the sentence uses two related words:

• hitamælir = thermometer
• mæla = to measure

That is why the sentence feels very logical in Icelandic: she finds the temperature-measurer and measures her temperature.

Hitann is the form of hiti, which can mean heat, temperature, or sometimes fever, depending on context.

In this sentence:

• mæla hitann sinn means measure one’s temperature

So even though the literal sense is measure the temperature, the natural English meaning is take her temperature or measure her temperature.

Because sinn is the reflexive possessive.

It refers back to the subject of the clause. Since the subject is hún (she), sinn means her own.

So:

• hitann sinn = her own temperature
• hitann hennar = her temperature, but often understood as someone else’s temperature, not the subject’s own

This is an important Icelandic distinction. If the possessor is the same as the subject, Icelandic usually prefers sinn/sín/sitt.

In Icelandic, possessive words can often come after the noun, and with sinn this is very common.

So:

• hitann sinn = her own temperature

This word order is normal and natural. English usually puts possessives before the noun (her temperature), but Icelandic often places them after, especially in expressions like this.

Because sinn has to agree with the noun it belongs to, not with the person who owns it.

Here it belongs to hitann, which is:

• masculine
• singular
• in the required case here

So the correct form is sinn.

Other forms include:

• sinn
• sína
• sitt
• sínum, etc.

For example:

• höndina sína = her/his own hand
• barnið sitt = her/his own child
• skóna sína = her/his own shoes

Because Icelandic, like English, often omits the repeated subject when two verbs share the same subject.

So:

• Hún finnur hitamælinn í baðherberginu og mælir hitann sinn.

means:

• She finds the thermometer in the bathroom and measures her temperature.

You could say og hún mælir hitann sinn, but it is not necessary here because the subject is clearly still hún.

Yes. Icelandic uses compound words very heavily.

Here:

• hitamælir = hita + mælir

  • roughly heat/temperature + measurer
  • so, thermometer

• baðherbergi = bað + herbergi

  • bath + room
  • so, bathroom

This is very common in Icelandic and is one reason long words often become easier once you learn to break them apart.

The first part is:

• Hún finnur hitamælinn í baðherberginu
• She finds the thermometer in the bathroom

This follows a common pattern:

• subject
  • verb
    • object
      • place

Then the second part is:

• og mælir hitann sinn
• and measures her temperature

So the whole sentence is straightforward, but it also shows several classic Icelandic features at once:

• verb forms like finnur and mælir
• the definite article attached to nouns
• case after í
• reflexive possession with sinn