From Proto-Germanic*sebun, from Proto-Indo-European*septḿ̥.
Cognate with Old High German sibun (German sieben), Old Saxon siƀun (Dutch zeven), Old Norse sjau (Swedish sju), Gothic 𐍃𐌹𐌱𐌿𐌽; and, outside the Germanic languages, with Sanskrit सप्तन्(saptán), Ancient Greek ἑπτά, Latin septem (see there for further descendants), Albanian shtatë, Old Irish secht (Irish seacht), Old Church Slavonic сєдмь.