Questions & Answers about Der Eindruck ist negativ.
Both are possible; they just say slightly different things.
Der Eindruck ist negativ.
→ The impression is negative.
You are talking about a specific impression that is already known from context. It’s like saying that/the impression.Ein Eindruck ist negativ.
→ An impression is negative.
This would sound unusual in most contexts; it suggests there are several impressions and you’re picking one of them, but it’s not a natural way to say it here.
In most normal contexts, speakers use der Eindruck because they mean the overall/general impression or the impression (someone makes), which is understood as a specific, known thing.
Because the noun Eindruck is grammatically masculine in German.
- Eindruck → masculine noun
- Nominative singular article: der Eindruck
- Accusative singular: den Eindruck
- Dative singular: dem Eindruck
- Genitive singular: des Eindrucks
German noun gender is largely arbitrary; you just have to learn der Eindruck as a unit. There is no simple rule that predicts the gender here.