When there is no article (or after numbers, viel, wenig, etwas), the adjective takes the endings of the definite article itself – it has to do all the work.
| masculine | feminine | neuter | plural | |
|---|---|---|---|---|
| Nom. | guter Wein | frische Milch | kaltes Wasser | nette Leute |
| Akk. | guten Wein | frische Milch | kaltes Wasser | nette Leute |
| Dat. | gutem Wein | frischer Milch | kaltem Wasser | netten Leuten |
| Gen. | guten Weins | frischer Milch | kalten Wassers | netter Leute |
Compare with der/die/das: der → guter, die → frische, das → kaltes, dem → gutem. Only genitive masc./neut. is -en.
Ich trinke gern heißen Tee mit frischer Milch.I like drinking hot tea with fresh milk.
Hier gibt es leckeres Essen und nette Leute.There is tasty food and nice people here.
Viele Grüße! Liebe Anna, …Best wishes! Dear Anna, … (letters)
The one principle behind all three tables
German wants the gender/case signal exactly once before the noun. If the article shows it (der, den, dem…), the adjective relaxes with -e/-en. If the article is missing or “naked” (ein), the adjective shows the signal (-er, -es, -em…).