寰 is a literary/classical character almost never used alone in modern Chinese. Look for it in compounds:
寰宇 (huányǔ, "the universe"),
寰球 (huánqiú, "the globe"),
人寰 (rénhuán, "the world of the living" — as in
惨绝人寰, "unprecedented in human history"), and
尘寰 (chénhuán, "the dusty world," Buddhist for "this mortal life"). Originally meant the royal domain within 1000 li of the imperial capital.
