cow-pox (n.)

"female of a bovine animal," especially the domestic ox, Middle English cu, qu, kowh, from Old English cu "cow," from Proto-Germanic *kwon (source also of Old Frisian ku, Middle Dutch coe, Dutch koe, Old High German kuo, German Kuh, Old Norse kyr, Danish, Swedish ko), earlier *kwom, from PIE root *gwou- "ox, bull, cow."

Applied to the females of various large animals from late 14c. As an insulting or degrading word for a woman, 1690s.

"disease characterized by eruptive sores," late 15c., spelling alteration of pockes (late 13c. in this sense), plural of pocke "pustule" (see pock (n.)). Especially (after c. 1500) of syphilis.