1. A royal jurisdiction or domain; a region which is under the dominion of a king; a kingdom. The absolute master of realms on which the sun perpetually alone. (Motley)
2. Hence, in general, province; region; country; domain; department; division; as, the realm of fancy.
Origin: OE. Realme, ream, reaume, OF. Reialme, roialme, F. Royaume, fr. (assumed) LL. Regalimen, from L. Regalis royal. See Regal.