-ie
Nouns ending in -ie are almost always die.
Names a field of study or an art.The words came from Greek.
Examples
- die Familie
- die Linie
- die Energie
- die Chemie
- die Biologie
- die Theorie
- die Therapie
Plural
- die Theorie → die Theorien
- die Familie → die Familien
One exception
das Genie came from French and stayed neuter.
- das Genie
Same letters, different ending
- das Knie