Heiti potturinn er heitur.

No. That is a very common point of confusion.

In Ég heiti Jón, heiti is a verb form, from heita, meaning am called.

In Heiti potturinn er heitur, heiti is not a verb. It is an adjective form of heitur meaning hot.

So even though the form heiti looks familiar, here it is functioning as an adjective that goes with potturinn.

Because Icelandic adjectives change form depending on grammar.

Here, potturinn is definite: it means the pot / the hot tub. When an adjective comes before a definite noun, Icelandic normally uses the weak adjective form.

So:

• heitur pottur = a hot pot / a hot tub
• heiti potturinn = the hot pot / the hot tub

That is why the adjective changes from heitur to heiti.

Because the last heitur is a predicate adjective, not an adjective directly attached to the noun inside the noun phrase.

Compare the difference:

• heiti potturinn = the hot tub
  Here the adjective is inside the noun phrase, so it uses the weak form.

• Potturinn er heitur = The tub is hot
  Here the adjective comes after er and describes the subject, so it usually uses the strong form.

So even though the subject is definite, the adjective after er is still heitur, not heiti.

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

So:

• pottur = pot / tub
• potturinn = the pot / the tub

The ending -inn here is the definite article in this form.

So Icelandic often says the equivalent of pot-the rather than using a separate word before the noun.

Here is the breakdown:

• heiti
  adjective, weak, masculine, nominative, singular

• potturinn
  noun, masculine, nominative, singular, definite

• er
  verb, present tense of vera = to be

• heitur
  adjective, strong, masculine, nominative, singular

The noun and both adjectives are masculine singular nominative because they refer to the same subject.

Yes, very often.

Literally, it looks like hot pot, but in Icelandic heitur pottur commonly refers to a hot tub, especially the kind used for soaking.

So Heiti potturinn er heitur can sound like The hot tub is hot.

That may sound a little repetitive in English, but it is useful for showing the grammar difference between:

• heiti before the definite noun
• heitur after er

Yes.

Potturinn er heitur means The pot/tub is hot.

That sentence is simpler and more neutral. It does not build hot into the noun phrase itself.

By contrast, Heiti potturinn er heitur specifically identifies the thing as the hot tub and then says that it is hot.

So the difference is roughly:

• Potturinn er heitur = The tub is hot
• Heiti potturinn er heitur = The hot tub is hot

Because Icelandic adjectives must agree with the noun they describe in gender, number, and case.

Since potturinn is masculine singular nominative, the adjective forms must match that:

• heiti matches it before the noun
• heitur matches it after er

The two adjectives differ only because one is weak and the other is strong, not because they refer to different things.

A rough learner-friendly pronunciation is:

HAY-tih POHT-ur-rinn er HAY-tur

A few useful notes:

• Stress is usually on the first syllable of each word.
• ei sounds roughly like ay in say.
• In potturinn, the tt is often pronounced with preaspiration, so it can sound a bit like ht.
• The r is usually tapped or rolled.

So potturinn may sound a little closer to POH-htur-rin than to a simple English potterin.