-ig
Nouns ending in -ig are almost always der.
Not a living ending — these words simply end this way.
Examples
- der Honig
- der König
- der Essig
- der Käfig
- der Pfennig
Plural
- der König → die Könige
One exception
das Reisig is the twigs taken as one heap, and a word like that is das.
- das Reisig