Deine Idee ist höchst interessant.

to be

Breakdown of Deine Idee ist höchst interessant.

• interessant: interesting
• die Idee: the idea
• dein: your

Questions & Answers about Deine Idee ist höchst interessant.

Why is it deine and not dein?

German possessive pronouns (mein, dein, sein, ihr, unser, euer, Ihr) change their ending to match the gender, number, and case of the noun they refer to, not the owner.

• The noun here is Idee.
• Idee is feminine: die Idee.
• It is the subject of the sentence, so it’s in the nominative case.
• Feminine nominative after a possessive pronoun takes -e: deine Idee.

So:

• dein Vater (masculine nominative)
• deine Mutter (feminine nominative)
• deine Ideen (plural nominative)

What case is deine Idee, and how can I tell?

Deine Idee is in the nominative case, because it is the subject of the sentence – the thing that “is interesting.”

You can test it by asking:

• Who or what is interesting? → Deine Idee.

That “who/what” question usually points to the nominative subject. The verb ist also agrees with a singular subject.

What is the gender of Idee, and how do I know?