This has to do with grammatical gender. You have: - masculine: ein neuer Tisch - feminine: eine neue Lampe - neuter: ein neues Haus. So it depends on the gender of the noun. The neuter forms have the "s" at the end. And then you have "etwas neues, etwas besonderes, nichts anderes" and such. In These case you have "etwas" or "nichts", which are both neuter and require the same form of the adjective. When you use the definite article (der/die/das), the declension of the adjectives is different: - der neue Tisch - die neue Lampe - das neue Haus You should find a complete list of these endings in any grammar book. As a native speaker, I don't have one.