No. The argument in the OP depends on a specific definition of omniscient; namely "all knowing." The following wouldn't work: (Macmillan) infinitely wise.
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I think part of your post is missing.
But the only definition of Omniscient I have ever heard is "all knowing". that is precisely the definition of the word as used today.
In any case, yes he was addressing a specific definition of omniscient,,,the most common one, and the only one which fits the etymology of the word. I was also addressing that definition.
omniscient
To be omniscient is to know everything. This often refers to a special power of God.
If you combine the Latin roots
omnis (meaning "all") and
scientia(meaning "knowledge"), you'll get
omniscient, meaning "knowledge of all." This is how a god is supposed to know when you sinned, or what's going to happen in the future.
If merely knowing something makes one omniscient, then even monkeys are omniscient.