閉鎖【へいさ】
closing, closure, shutdown, lockout
封鎖【ふうさ】
blockade, lockdown, sealing off (an area), freezing (funds)
鎖【くさり】
chain, chains
鎖国【さこく】
national isolation, closing the country (to foreigners), sakoku, policy of national isolation enacted by the Tokugawa shogunate