Synonyms for Realm:

adj.

regional (adjective)
local, regional, national, county, canton, riding, provincial, quarter, precinct, borough, tract, district, commonwealth, area, circuit, divisional, sector, city, zone, town, state, colonial, shire, territorial.

n.

accede, commoner, the crown, court, accession, dethrone, coronation, depose, crown, abdicate. compass, swing, scope, orbit, range, ambit, sphere, sweep, reach, extent, extension, purview. scene, bag, department, subject, terrain, world. area of responsibility or rule (noun)
domain, neighborhood, turf, territory, ground, place, range, province, region, country, empire, zone, department, field, purview, scope, compass, world, orbit, extent, kingdom, dominion, land, reach, state, sweep, sphere.
arena (noun)
domain, enclosure, region, arena, dominion, hippodrome, ground, campus, locale, hall, gallery, stage, beat, pen, precinct, circle, auditorium, area, ring, bailiwick, colosseum, room, battlefield, amphitheater, circuit, gymnasium, circus, field, courtyard, battle-ground, turf, theater, province, setting.
cognition (noun)
region.
domain (noun)
department, sphere, range.
extent (noun)
range.
location (noun)
kingdom.
possession (noun)
acquisition, possession, property, holding, territory, wealth, worth, effects, kingdom, land, empire.
property (noun)
chattel, belongings, fixtures, real estate, Resources, stock, realty, inheritance, estate, assets, farm, manor, principal, legacy, ranch, goods, possessions, title.
region (noun)
colony, county, locality, place, plot, quarter, neighborhood, shire, canton, dukedom, duchy, city, commonweal, country, lot, earldom, nation, state, district, riding, tract, town, division, borough, sector, zone, parcel, municipality.

Other synonyms:

purview. ambit, world, orbit. bag, terrain, extent. compass, sphere, department. scope. extension, subject, scene. Other relevant words:
world, crown, ambit, sphere, purview, extension, swing, compass, subject, range, department, scope, extent, sweep, reach, scene, bag, terrain, orbit.

Usage examples for realm

  1. These are the women who to- day are close upon the heels of man in the whole realm of thought, in art, in science, in literature and in government. – The Woman's Bible Part I. Comments on Genesis, Exodus, Leviticus, Numbers and Deuteronomy. Part II. Comments on the Old and New Testaments from Joshua to Revelation. by Elizabeth Cady Stanton
  2. But Hebrew was not enough; the vast realm of Knowledge, which he divined dimly, must lie in other languages. – Dreamers of the Ghetto by I. Zangwill