badger: [16] The Old English term for a ‘badger’ was brock, a word of Celtic origin, and badger does not begin to appear, somewhat mysteriously, until the early 16th century. The name has never been satisfactorily explained, but perhaps the least implausible explanation is from the word badge, in reference to the white stripes on the animal’s forehead, as if it were wearing a badge (a term originally applied to a distinctive device worn by a knight for purposes of recognition); the early spelling bageard suggests that it may have been formed with the suffix -ard, as in dullard and sluggard. (Badge itself is of even more obscure origin; it first turns up in Middle English, in the mid 14th century.) Other early terms for the badger were bauson (14th– 18th centuries), from Old French bausen, and grey (15th–17th centuries).
badger (n.)
1520s, perhaps from bage "badge" (see badge) + -ard "one who carries some action or possesses some quality," suffix related to Middle High German -hart "bold" (see -ard). If so, the central notion is the badge-like white blaze on the animal's forehead (as in French blaireau "badger," from Old French blarel, from bler "marked with a white spot;" also obsolete Middle English bauson "badger," from Old French bauzan, literally "black-and-white spotted"). But blaze (n.2) was the usual word for this.
An Old English name for the creature was the Celtic borrowing brock; also græg (Middle English grei, grey). In American English, the nickname of inhabitants or natives of Wisconsin (1833).
badger (v.)
1790, from badger (n.), based on the behavior of the dogs in the medieval sport of badger-baiting, still practiced in 18c. England. Related: Badgered; badgering.