To know thoroughly or completely; to make known; an archaic or obsolete verb.
From 'be-' (Old English prefix meaning thoroughly or around) plus 'know' (from Old English 'cnāwan'). The prefix intensifies the action of knowing, suggesting complete or comprehensive knowledge.
English once had 'beknow' alongside 'know,' just as it had 'belie' alongside 'lie'—these 'be-' verbs have almost entirely disappeared, making them linguistic fossils that show how English speakers once preferred more emphatic verb forms.
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