That misspelling is mine. The original poster spelled it correctly. I convert the schwa to an a every time, because the actual spelling seems like “There, Min.” which does not match to the pronunciation.
I have a few words I do that with and Theremin is one of those words.
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I’ve never done well with “What was the author’s intent?” questions and still don’t so I shoot for explicit to avoid misunderstandings in communication.
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