Knows or understands something; to have knowledge of (Scottish and archaic English usage).
From Old English 'cennan' and Old Norse 'kenna' meaning 'to know or teach.' Still used in Scottish English but archaic in standard English.
In Scottish English, people still say 'I dinna ken' (I don't know)—it's the same root that became 'canny' (careful, shrewd), because knowing things made you clever!
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