Kennarinn skrifar samheitið á töfluna.

Because Icelandic usually puts the definite article on the end of the noun instead of using a separate word like the.

• kennari = teacher
• kennarinn = the teacher

Here, -inn is the masculine singular definite ending in the nominative case.

So:

• kennari skrifar = a teacher writes
• kennarinn skrifar = the teacher writes

Skrifar is the 3rd person singular present tense form of the verb skrifa.

The basic dictionary form is:

• að skrifa = to write

But in a sentence, the verb changes form:

• ég skrifa = I write
• þú skrifar/skrifir? actually standard is þú skrifar only in some dialect? No, standard is þú skrifar? Wait, for weak verbs like skrifa, standard present is ég skrifa, þú skrifar, hann/hún/það skrifar. Yes.
• hann/hún/það skrifar = he/she/it writes

Since kennarinn is a singular subject, the sentence uses skrifar.

The noun is samheiti, which is a neuter noun.

Its forms are:

• samheiti = a synonym
• samheitið = the synonym

The ending -ð here is the definite article for a neuter singular noun.

In this sentence, samheitið is the direct object of skrifar. For neuter nouns like this one, the nominative and accusative singular are often the same, so the form stays samheitið.

Because Icelandic often changes case after a preposition depending on whether the idea is:

• location = where something is
• direction/movement = where something goes

With á:

• á + accusative often suggests movement or direction onto something
• á + dative often suggests being on something

So:

• á töfluna = onto the board
• á töflunni = on the board

In this sentence, the idea is that the writing is being put onto the board, so á töfluna is used.

This is a normal noun change in Icelandic.

The basic noun is:

• tafla = board

But when it changes case and takes the definite article, the form changes:

• tafla = a board
• töflu = a board (accusative/dative forms, depending on context)
• töfluna = the board (accusative singular)

The vowel change from a to ö is part of the noun’s regular pattern. Many Icelandic nouns change their stem vowel in different forms, so this is something learners gradually get used to.

It is accusative singular definite.

Why accusative?

Because after á, Icelandic often uses the accusative when there is direction or movement toward a surface or place. In this sentence, the board is the target surface.

Why singular definite?

Because -na here includes the feminine singular definite ending.

So töfluna is:

• feminine
• singular
• accusative
• definite

This sentence has a very straightforward word order:

• Kennarinn = subject
• skrifar = verb
• samheitið = direct object
• á töfluna = prepositional phrase

So it follows a basic pattern similar to English:

Subject + Verb + Object + Place/Direction

That said, Icelandic word order can be more flexible than English, especially because case endings help show what each word is doing. But this sentence is a very normal, neutral way to say it.

In this sentence:

• Kennarinn is the subject
• samheitið is the object

You can tell this mainly from:

1. Meaning and sentence structure

   • The teacher is the one doing the writing.
   • The synonym is the thing being written.

2. Case

   • kennarinn is nominative
   • samheitið is functioning as the accusative object

One tricky point is that samheitið looks the same in nominative and accusative, because neuter nouns often have identical forms in those two cases. So here, learners usually rely on syntax and meaning as well as case knowledge.

Yes. All three noun phrases are definite.

• kennarinn = the teacher
• samheitið = the synonym
• töfluna = the board

This is very common in Icelandic: instead of a separate word like the, definiteness is usually shown by an ending attached to the noun.

So one sentence can contain several definite nouns without needing a separate article word each time.

Yes, it is.

It is made from:

• sam- = same, together, corresponding
• heiti = name, term

So samheiti is literally something like a same-term or equivalent term, which is why it means synonym.

This is useful to notice because Icelandic forms many words through compounds, and recognizing the parts can make vocabulary easier to remember.