Progressive clue challenge

How quickly can you identify the hidden word?

Begin with a broad grammatical clue. Reveal more only when needed. Fewer clues and fewer wrong guesses produce a higher score.

100
It is used as a noun.
It begins with “M” and contains 7 letters.
Definition: A substance regarded as an anhydride of meconinic acid, existing in opium and extracted as a white crystalline substance. Also erroneously called meconina, meconia, etc., as though it were an alkaloid.
It ends with “N”.
Clue 1 of 4 is visible.
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