siður

From Old Norse siðr (“a custom, a habit; conduct, morality, religion”), from Proto-Germanic *siduz, from Proto-Indo-European *swe-dh-. Cognate to Old English sidu (“a custom; a manner; a rite; purity”), Old High German situ (“a custom, a habit”) (whence the German Sitte), Faroese siður (“a tradition, a custom”), Swedish sed, Gothic 𐍃𐌹𐌳𐌿𐍃 (sidus), Ancient Greek ἦθος (êthos), from a Proto-Indo-European stem *swe-dh-.