-ich
Nouns ending in -ich are always der.
Not a living ending — these words simply end this way.
Examples
- der Teppich
- der Rettich
- der Kranich
- der Sittich
- der Estrich
Plural
- der Teppich → die Teppiche
Same letters, different ending
das Reich is not an -ich word: those letters are the word itself, and das Königreich and das Kaiserreich are built on it.
- das Reich
- das Königreich
- das Kaiserreich