The quality or state of being attempered; moderation or regulation; the act of adjusting or moderating.
From attemper + -ance suffix (similar formation to 'temperance'). This rare variant emphasizes the process of adjustment rather than the quality of moderation.
This word is basically the neglected sibling of 'temperance'—they mean similar things, but 'temperance' (meaning moderation/sobriety) won the language game, leaving 'attemperance' stranded in old medical and philosophical texts.
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