Most German nouns do not change when the case changes. A small but common group of masculine nouns does: it adds -n or -en everywhere except the nominative singular.
Der Student kommt. — The student is coming.
Ich sehe den Studenten. — I see the student.
This pattern is called N-declension or the weak masculine declension. The article shows the case as usual; the noun quietly changes with it.
The one pattern
Use der Student as the model.
| Case | Singular | Plural |
|---|---|---|
| nominative | der Student | die Studenten |
| accusative | den Studenten | die Studenten |
| dative | dem Studenten | den Studenten |
| genitive | des Studenten | der Studenten |
Only der Student has no ending. Every other box is Studenten. That includes the plural, so this noun has fewer distinct forms than the table first suggests.
Der Lehrer hilft dem Studenten. — The teacher helps the student.
Das ist das Buch des Studenten. — That is the student’s book.
The common nouns that follow it
The pattern mainly covers masculine words for people and animals. Many end in -e.
| Nominative | All other singular cases | Meaning |
|---|---|---|
| der Junge | den Jungen | boy |
| der Kunde | den Kunden | customer |
| der Kollege | den Kollegen | colleague |
| der Name | den Namen | name |
| der Hase | den Hasen | hare/rabbit |
| der Löwe | den Löwen | lion |
Another large group consists of international words with endings such as -ant, -ent, -ist, -oge and -at.
| Ending | Example |
|---|---|
| -ant | der Praktikant → den Praktikanten |
| -ent | der Präsident → den Präsidenten |
| -ist | der Journalist → den Journalisten |
| -oge | der Biologe → den Biologen |
| -at | der Kandidat → den Kandidaten |
These are useful clues, not a rule for every masculine noun. Learn the nominative together with one changed form: der Kunde — mit dem Kunden.
The article and noun both change
The most common error is to change only the article.
Ich spreche mit dem Kollegen. ✓
Ich spreche mit dem Kollege. ✗
The article tells you the case; the -n/-en tells you that this particular noun belongs to the weak group. One does not replace the other.
This also applies when an adjective sits between them.
Ich frage den neuen Kollegen. — I ask the new colleague.
Sie arbeitet mit einem netten Kunden. — She works with a nice customer.
Herr and a few special shapes
der Herr follows the idea but uses Herrn in the singular and Herren in the plural.
| Form | |
|---|---|
| nominative singular | Herr Müller |
| other singular cases | Herrn Müller |
| plural | die Herren |
Ich schreibe Herrn Müller. — I am writing to Mr Müller.
der Mensch becomes den Menschen. der Nachbar may use den Nachbarn. These do not advertise the pattern with an -e, so they are best learned as pairs.
Name, Gedanke and Glaube add one more letter
A few weak nouns take -n in the non-nominative singular but add -ns in the genitive.
| Nominative | Accusative/dative | Genitive |
|---|---|---|
| der Name | den/dem Namen | des Namens |
| der Gedanke | den/dem Gedanken | des Gedankens |
| der Glaube | den/dem Glauben | des Glaubens |
You will meet meines Namens often on forms and in formal language. It is worth treating der Name — den Namen — des Namens as its own fixed set.
Herz is mixed, not a normal weak noun
das Herz is neuter, but it partly resembles this pattern.
| Case | Form |
|---|---|
| nominative | das Herz |
| accusative | das Herz |
| dative | dem Herzen |
| genitive | des Herzens |
Because it is neuter and keeps Herz in the accusative, it is an exception beside N-declension rather than a member of the main masculine group.
How to catch the ending while speaking
When you use a masculine noun for a person, pause at den, dem, des, einen, einem. Ask whether you learned that noun with an -n/-en partner.
der Tourist → Ich sehe einen Touristen.
der Kunde → Ich helfe einem Kunden.
der Student → Das Zimmer des Studenten.
The nominative is the only bare singular form. If the man is not doing the action, the ending is likely to appear.
What to actually memorise
Memorise the contrast der Student — den Studenten, then learn new weak nouns in the same two-form format. Focus first on Junge, Kunde, Kollege, Mensch, Herr and the international endings -ant, -ent, -ist, -oge, -at.
Rules stick faster once you have met the words. Every example above links to its own page.
Practise in the trainer