Determiners "dieser" and "welcher"

Dieser ("this"/"that") points to a specific noun, and welcher ("which") asks which one is meant — and the good news is you already know how both behave. Both belong to a small family called der-words, and every der-word takes the exact same endings as der/die/das itself. Learn the pattern once on der/die/das, and dieser and welcher come for free.

Quick shortcut: replace the d in der/die/das/den/dem with dies- for "this" or welch- for "which" — the ending after it never changes: der → dieser/welcher, die → diese/welche, das → dieses/welches, den → diesen/welchen, dem → diesem/welchem.

The same endings as der/die/das

Because dieser and welcher are der-words, they take exactly the endings you already met with the definite article, the accusative article, and the dative article:

• Dieser Mann arbeitet hier. (This man works here.) — masculine, nominative
• Ich kenne diesen Mann. (I know this man.) — masculine, accusative
• Ich helfe diesem Mann. (I'm helping this man.) — masculine, dative
• Diese Frau kommt aus Berlin. (This woman comes from Berlin.) — feminine, nominative and accusative look the same (the dative is dieser, as the table above shows)
• Dieses Kind ist müde. (This child is tired.) — neuter, nominative/accusative look the same
• Diese Bücher sind neu. (These books are new.) — plural

In the dative plural, the noun itself normally adds -n too, just as it does after dem/der/den — ✅ mit diesen Büchern, ✅ mit welchen Freunden, not ❌ mit diesen Bücher (unless the noun already ends in -n or -s, like mit den Autos).

Because the endings are identical to der/die/das, an adjective placed after dieser or welcher takes exactly the same weak ending (-e or -en) it would take after der/die/das — see adjective endings after der-words for that pattern in full: dieser neue Mann, diese neue Wohnung, dieses neue Auto.

Dieser: pointing to something specific

Dieser singles out one particular thing, usually "this" (something close by, or already the topic of conversation) — English "that" often works just as well as a translation, since German doesn't force a this/that distinction the way English does:

• Dieser Rock gefällt mir. — I like this skirt.
• Diese Idee ist gut. — This idea is good.
• Dieses Restaurant ist teuer. — This restaurant is expensive.
• Ich möchte diese Schuhe kaufen. — I'd like to buy these shoes. (plural, accusative)

Dieser can also stand alone, without a noun, once the noun is already clear from context — the ending stays exactly the same:

• Welcher Mantel ist deiner? — Dieser. — Which coat is yours? — This one.

Welcher: asking "which"

Welcher asks the listener to pick one option out of a known set — a more specific question than was ("what"), which you met in W-questions. In an independent W-question, welcher normally takes position 1, with the conjugated verb immediately after it:

• Welcher Zug fährt nach Berlin? — Which train goes to Berlin?
• Welche Farbe magst du? — Which colour do you like?
• Welches Buch liest du gerade? — Which book are you reading right now?
• Mit welchem Bus fährst du? — Which bus do you take? (dative, after the preposition mit)

Welcher still has to agree with the noun it refers to — whether stated or understood from context — not with the answer you expect: welche agrees with die Farbe (feminine) even when you're talking about a masculine object, e.g. der Rock.

Common mistakes

• ❌ Dieser Frau ist nett. → ✅ Diese Frau ist nett. (Frau is feminine, so the nominative form is diese, not the masculine dieser)
• ❌ Ich kenne dieser Mann. → ✅ Ich kenne diesen Mann. (direct object of a masculine noun needs the accusative ending -en, exactly like den)
• ❌ Welche Buch liest du? → ✅ Welches Buch liest du? (Buch is neuter, so welcher needs the neuter ending -es, not the feminine/plural -e)
• ❌ Treating dieser like an unchanging word (as in English "this") → ✅ it declines for gender and case just like der/die/das — the ending always has to match the noun

Quick check

Fill in the correct form of dieser or welcher.

1. ____ Auto ist neu. (dieser — neuter, nominative)
2. Ich sehe ____ Frau. (dieser — feminine, accusative)
3. ____ Bus fährt zum Bahnhof? (welcher — masculine, nominative)
4. Ich helfe ____ Kind. (dieser — neuter, dative)
5. Mit ____ Zug fährst du? (welcher — masculine, dative)

Key takeaways

• Dieser ("this"/"that") and welcher ("which") are der-words — they take exactly the same endings as der/die/das in every case: nominative dieser/diese/dieses/diese, accusative diesen/diese/dieses/diese, dative diesem/dieser/diesem/diesen.
• The ending always agrees with the noun's own gender, number, and case — not with anything else in the sentence.
• An adjective placed after dieser/welcher takes the same weak ending (-e/-en) it would take after der/die/das.
• Dieser can stand alone once the noun is clear from context, keeping its usual ending.
• Welcher is a W-question word: it takes position 1, with the conjugated verb right after it, and still agrees with the noun it's asking about.