Un-seal is a word that means to remove a seal or barrier from something. When we un-seal something, we open it up, making it accessible or available. Antonyms for un-seal, on the other hand, are words that describe closing, sealing or obscuring something. These words would include seal, lock, fasten, close, shut, conceal, cover, and block. In practical terms, antonyms for un-seal might be used when we want to reseal a package, lock a door or conceal an object. Antonyms can help us understand the nuances of language and allow us to convey our thoughts and intentions more clearly.