地域【ちいき】
area, region, district, locality
区域【くいき】
limits, boundary, domain, zone, sphere, territory, area (e.g. in programming languages)
領域【りょういき】
area, domain, territory, field, range, region, regime
流域【りゅういき】
drainage basin, catchment basin, river basin, watershed, valley
聖域【せいいき】
sacred precincts, sanctuary, consecrated ground, holy ground, issue that is regarded as being off-limits, matter that is not up for discussion