The act of darkening or obscuring; the condition of being obscured or confused; dimness or darkness, especially of vision.
From Latin caligatio, derived from caligare (to darken), plus English -tion suffix. The term combines Latin root and English abstract noun formation, used in medical and philosophical texts.
This noun represents a whole medical concept now forgotten—medieval doctors actually had a category of blindness they called 'caligation,' treating it as a condition of obscured sight distinct from complete blindness, showing how precise older medical terminology could be.
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