seal off(redirected from seal up)
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Also, seal up. Close tightly or barricade to prevent entry or exit. For example, We're sealing off the unused wing of the building, or The jar is tightly sealed up. Dating from the first half of the 1900s, this idiom uses seal in the sense of "close securely," as one used to do with a seal of wax.
1. To close tightly or surround something or someplace with a barricade or cordon: The government has sealed off its borders. The police surrounded the building and sealed it off.
2. To isolate someone or something: The remote location sealed the village off from the rest of the world.