The Indefinite Article: ein, eine

The German word for "a" or "an" is ein for masculine and neuter nouns, and eine for feminine nouns. Like English "a/an," it introduces a noun that is non-specific — a man (some man, not a particular known one) rather than the man. That much is straightforward. But hiding inside the indefinite article is one of the most consequential little facts in German grammar: in the nominative, ein has no ending at all for masculine and neuter nouns. That missing ending is not a flaw or an oversight — it is the trigger for an entire system of adjective endings. Understanding why ein is sometimes endingless is the key to a lot of German that comes later.

The basic forms

Notice the symmetry — and the asymmetry. Masculine and neuter both use the bare form ein. Only feminine adds an ending: eine. This is the opposite of what English-speaker intuition expects, because in English "a" never changes for gender at all.

The crucial gap: ein has NO ending in masculine and neuter nominative

Compare the definite and indefinite articles side by side in the nominative:

The definite article always has a clear, gender-revealing ending: der screams "masculine," das screams "neuter." The indefinite article ein for both masculine and neuter looks identical — it gives you no information about which gender it is. The ending that would tell you (the -r of der, the -s of das) is simply absent.

Why the missing ending makes the adjective work harder

Here is the payoff, and the insight competitors skip. German wants the gender and case of a noun phrase to be marked somewhere. With the definite article, the article itself does it (der, das). But when you use ein and the ending is missing, the job falls to the adjective. The adjective steps up and takes the strong ending — the same -r or -s the article failed to show:

Look at guter and gutes: the adjective carries the -er (masculine) and -es (neuter) that ein couldn't. Now compare the feminine, where eine already shows its ending, so the adjective relaxes into a plain -e:

This is the famous "mixed declension": after ein-words, the adjective takes the strong ending exactly where the article is endingless (masculine and neuter nominative, plus neuter accusative), and a weak ending everywhere else. So the seemingly tiny fact "ein has no ending" is the trigger for the entire mixed adjective-declension system. (See mixed adjective declension for the full picture.)

ein has no plural

In English, "a book" pluralizes to "books" — the article just vanishes. German works exactly the same way: ein has no plural form. The plural of ein Buch is simply Bücher (books), with no article at all.

There is no such thing as eine Bücher meaning "some books." If you want to express "some" explicitly, German uses einige (some) or ein paar (a few), but the indefinite article itself has no plural.

When German drops ein where English keeps "a"

There is one place where English insists on "a" but German leaves it out: stating someone's profession, nationality, or religion after the verbs sein (to be) and werden (to become). English says "She is a doctor"; German says "She is doctor" — no article.

The logic is that the profession is being treated as a category you belong to, not as one specific instance of a thing. The article comes back, though, the moment you add a describing adjective, because then you are picking out a particular kind:

So Er ist Student (he's a student, plain category) but Er ist ein fleißiger Student (he's a hard-working student, qualified). This drop-the-article rule is a frequent stumbling block for English speakers, who reflexively insert ein.

Negation uses kein, not "nicht ein"

When you want to say "not a" or "no" — the negative of the indefinite article — German does not say nicht ein. It uses a dedicated negative article, kein (no, not a, not any), which declines exactly like ein but, unlike ein, does have a plural:

The plural form keine fills the gap that ein leaves empty. (See kein for the full negation rules.)

Common mistakes

Key takeaways

• The indefinite article is ein for masculine and neuter, eine for feminine, used for non-specific singular nouns, like English "a/an."
• In the nominative, masculine and neuter ein has no ending — unlike der and das, it gives no gender signal.
• That missing ending is the trigger for the mixed adjective declension: the adjective takes the strong ending (ein guter Mann, ein gutes Kind) to carry the gender that ein couldn't.
• ein has no plural — "books" is just Bücher. Use einige or ein paar for "some/a few."
• German drops ein before an unmodified profession/nationality after sein/werden: Sie ist Ärztin. The article returns when an adjective is added: eine gute Ärztin.
• The negative of ein is kein (which does have a plural, keine), never nicht ein.
• Next, learn how ein changes across the four cases in the ein-word declension table.