H. P. Grice, "On knowing and knowledge"

knowledge (n.)

early 12c., cnawlece "acknowledgment of a superior, honor, worship."

For first element see know (v.). 

Grice:

"The second element, '-ledge,' I regret to say remains obscure.'

''-Ledge' is perhaps from some Scandinavian dialect, and perhaps, but perhaps not, cognate with the -lock "action, process," found in wedlock."

"In which case Ryle would be right and 'knowing' WOULD be a bit of an action, a bit of a process."

From late 14c. as "capacity for knowing, understanding; familiarity;" also "fact or condition of knowing, awareness of a fact;" also "news, notice, information; learning; organized body of facts or teachings." 

Sense of "sexual intercourse" is from c. 1400. 

Middle English also had a verb form, knoulechen "acknowledge" (c. 1200), later "find out about; recognize," and "to have sexual intercourse with" (c. 1300).

Compare acknowledge.