Tíminn hjá tannlækninum er á morgun.

In Icelandic, tími has several meanings depending on context. It can mean:

• time
• an hour / a period of time
• a class period
• an appointment

In medical, dental, and office contexts, tími very often means appointment. So tíminn hjá tannlækninum is understood as the dentist appointment or more naturally the appointment with the dentist.

The ending -inn is the suffixed definite article in Icelandic. So:

• tími = an appointment / time
• tíminn = the appointment / the time

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

Hjá often means with, at, or by, depending on context. With people and professions, it is commonly used to mean:

• with someone
• at someone’s place or practice

So hjá tannlækninum can be understood as:

• with the dentist
• at the dentist’s

That is why this is a natural way to talk about an appointment with a professional in Icelandic.

Because hjá requires the dative case, and tannlækninum is the dative singular definite form of tannlæknir.

Here is the basic idea:

• tannlæknir = dentist
• tannlækninum = the dentist in the dative

So the form changes because Icelandic nouns change form after certain prepositions, and hjá is one of those prepositions.

Because the sentence is talking about a specific, known appointment with a specific dentist. Icelandic often uses the definite form when the person or thing is understood from context.

Compare:

• hjá tannlækni = with a dentist / at a dentist
• hjá tannlækninum = with the dentist / at the dentist’s

In this sentence, the definite form sounds natural because it refers to the particular dentist connected with that appointment.

Icelandic often uses the present tense for scheduled future events, just like English does.

So:

• Tíminn er á morgun = literally The appointment is tomorrow

This does not mean the appointment is happening right now. It means that its scheduled time is tomorrow. This is completely normal Icelandic usage.

Á morgun is the normal Icelandic expression for tomorrow. It is best learned as a fixed phrase.

Literally, it contains the preposition á, but in practice you should think of á morgun as one unit meaning tomorrow.

This is different from English, where tomorrow is a single word. Icelandic often uses short prepositional expressions where English uses one adverb.

Yes. Icelandic word order is flexible, although not completely free.

The sentence as given:

• Tíminn hjá tannlækninum er á morgun.

is a neutral way to say it.

You could also say:

• Á morgun er tíminn hjá tannlækninum.

That puts more focus on tomorrow.

Both are grammatical. Icelandic often moves time expressions to the front for emphasis, but the verb still stays in second position, which is an important pattern in Icelandic sentence structure.

Either can be right, depending on how natural you want the English to sound.

• with the dentist focuses on the person
• at the dentist’s focuses on the place or appointment context

In Icelandic, hjá can cover both ideas. So tíminn hjá tannlækninum naturally refers to the dental appointment without needing to choose as strictly between those two English versions.