Immense means very large in size, amount, or degree. You might describe the ocean as immense, or your homework load, or the slice of cake your brother took, leaving you a tiny sliver.
This word has an immense number of near synonyms: huge, great, enormous, vast, gigantic, colossal, mammoth, copious, tremendous are a few of the more common ones. If you're having immense difficulty deciding which word to use, just plain "very big" might do.
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