Jeg er for trøtt i kveld.

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Breakdown of Jeg er for trøtt i kveld.

• være: to be
• i: in
• kvelden: the evening

Questions & Answers about Jeg er for trøtt i kveld.

What does for trøtt mean, and how is for used here?

In this sentence, for means too.

• Jeg er for trøtt i kveld = I am too tired tonight.
• Pattern: for + adjective = too + adjective
  
  • for trøtt = too tired
  • for kald = too cold
  • for dyr = too expensive

This for is different from the preposition for that means things like for, to, about in other contexts. Here it is an adverb modifying the adjective trøtt.

Could I say Jeg er trøtt for i kveld instead?

No. For must come directly before the adjective it modifies.

Correct:

• Jeg er for trøtt i kveld.

Incorrect:

• Jeg er trøtt for i kveld. ✗

So the order is: subject + verb + for + adjective + time expression.

Why is it trøtt and not trøtte? Do adjectives change with the subject?

Norwegian adjectives do change form, but in this position (after er, describing the subject), they usually stay in the basic singular form.

• Jeg er trøtt. (I am tired.)
• Du er trøtt. (You are tired.)
• Han / hun er trøtt. (He / she is tired.)

For plural subjects, it changes:

• Vi er trøtte. (We are tired.)
• De er trøtte. (They are tired.)

So with jeg, trøtt is the correct form.