Where does “-ej” come from?

-ej (Polish) comes from Proto-Slavic -ějь, from Proto-Balto-Slavic -ēˀjas.

Ancestry of “-ej”, step by step

StepLanguageWordMeaning
1Proto-Slavic-ějьDeverbal from stative verbs inflecting in *-ěti....
2Proto-Balto-Slavic-ēˀjas—

Words derived from “-ej”

Every word from Proto-Balto-Slavic -ēˀjas →Every word from Proto-Slavic -ějь →