Meaning

adjective showing self-interest and shrewdness in dealing with others

originNorthern English dialect, from can (“to know”) ( + -y), from Middle English can, first and third person singular of cunnen, connen (“to be able, know how to”), from Old English cunnan (“to know how to, be able to”). Compare Scots canny, English cunny, Old English cann (“knowledge, assertion”). More at can, cunning.

Etymology from Wiktionary, CC BY-SA 3.0