A vegetable plant of which, depending on the variety, either the root bulb (celeriac) or the fleshy leaf stalks (celery) are eaten as a seasoning vegetable or as a vegetable in their own right.
example
Für einen klassischen Waldorfsalat braucht man Äpfel, Walnüsse und Knollensellerie.
For a classic Waldorf salad, you need apples, walnuts, and celeriac.
Usage tips
Two varieties
The word 'Sellerie' (celery) can refer to two different kinds of vegetable. To distinguish them, German uses 'der Knollensellerie' (celeriac) for the round root and 'der Staudensellerie' (or 'Stangensellerie') for the green stalks.
EXAMPLE
Für die Suppe brauche ich eine halbe Knolle Knollensellerie.
For the soup, I need half a bulb of celeriac.
Part of soup greens
In Germany, (celeriac) 'Sellerie' is a standard part of 'Suppengrün' (also called 'Suppengemüse'), a bundle of soup vegetables. This bundle, usually with carrots and leek, is the base for many soups and sauces.
EXAMPLE
Im Supermarkt kaufe ich immer ein Bund Suppengrün für die Brühe.
At the supermarket, I always buy a bunch of soup greens for the broth.
Regional variant
Especially in Austria, the term 'der Zeller' is also very commonly used for celery/celeriac.
EXAMPLE
Für das Schnitzel brauchen wir noch Semmelbrösel und Zeller.
For the schnitzel, we still need breadcrumbs and celery.