To dim, obscure, or make dark; to cloud or obscure someone's understanding or perception.
From Latin caligatus, past participle of caligare, derived from caliga (darkness). The verb entered English in the 16th century, used in both literal and figurative senses to describe obscuring or confusing.
This verb is beautifully archaic—'to caligate one's vision' sounds like something a wizard would do in a fantasy novel, but it's real English from the 1500s, a poetic way to say 'make dark' that we've mostly forgotten.
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