HALIDOM

Hal″i‐dom (hăl″ĭ‐dŭm), n. [[AS. hāligdōm holiness, sacrament, sanctuary, relics; hālig holy + -dōm, E. -dom. See Holy.]] 1. 1. Holiness; sanctity; sacred oath; sacred things; sanctuary; — used chiefly in oaths.
So God me help and halidom. Piers Plowman. By my halidom, I was fast asleep. Shak. 2. 2. Holy doom; the Last Day. Shipley.