A big, thorough clean of a whole house — not the usual wiping and sweeping, but the once-a-year kind where you move the furniture, wash the curtains, empty the cupboards and throw things away. The name comes from a real old habit in cold countries: through the winter the house was shut up with coal or wood fires burning inside, so everything got sooty, and when spring finally came people threw open the windows and cleaned the whole place. Taiwan has almost exactly the same custom at a different time — 大掃除 before Lunar New Year — so the meaning will feel familiar even though the season does not match. That difference matters when you translate: an English spring-clean happens in spring, and if you mean the New Year one you may need to say so. The word is also used for things that are not houses. A company can have a spring-clean of its files; you can spring-clean your phone, your email, your bookshelf. In those uses the idea kept is "go through everything properly and get rid of what you do not need". You can write it spring-cleaning or spring cleaning, and there is a verb too: to spring-clean, spring-cleaned.