"to learn to know, inquire into," from Old English cunnian "to learn to know," ultimately from the same ancient root as can (v.1) and compare con (v.3). Surviving into 17c. and perhaps later in dialects. Also compare cunning.
cumulation
cumulative
cumulo-
cumulous
cumulus
cun
Cunard
cunctator
cuneate
cuneiform
cunnilingus