Relating to or containing antimony in its lower oxidation state, or describing compounds where antimony has a lower valence.
From antimony + -ious (variant of -ous, meaning 'of or relating to'). In chemistry, -ious typically denotes a lower oxidation state than -ic (e.g., antimonious vs. antimonic, ferrous vs. ferric).
Antimonious and antimonic are chemically different substances with confusingly similar names—this is why scientists use oxidation numbers today instead of relying on -ous and -ic endings, which confused even chemists historically.
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