Where does “sith” come from?

sith (Old Danish) comes from Old Norse siðr, from Proto-Germanic siduz, from Proto-Indo-European swedʰ- — custom, habit; wont, habit, custom.

Ancestry of “sith”, step by step

StepLanguageWordMeaning
1Old Norsesiðra custom, a habit; a conduct, morality, religion
2Proto-Germanicsiduzcustom, habit, practice; conduct
3Proto-Indo-Europeanswedʰ-custom, habit; wont, habit, custom

Words derived from “sith”

Every word from Proto-Indo-European swedʰ- →Every word from Proto-Germanic siduz →Every word from Old Norse siðr →