a chip on (one's) shoulder

a chip on (one's) shoulder

An attitude that leads one to become combative or easily angered. Fred has such a chip on his shoulder—you never know what's going to set him off next. She won't admit it, but Kate has a chip on her shoulder when it comes to discussing her career.
See also: chip, on, shoulder
Farlex Dictionary of Idioms.

*chip on one's shoulder

Fig. a bad attitude that tends to get someone easily upset. (*Typically: get ~; have ~; give one ~.) Why did you get so angry at the slightest criticism? You seem to have a chip on your shoulder.
See also: chip, on, shoulder
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

chip on one's shoulder

A belligerent attitude or grievance, as in Mary is easily offended; she always has a chip on her shoulder. This term actually was defined in a newspaper article ( Long Island Telegraph, May 20, 1830): "When two churlish boys were determined to fight, a chip would be placed on the shoulder of one and the other demanded to knock it off at his peril." [Early 1800s]
See also: chip, on, shoulder
The American Heritage® Dictionary of Idioms by Christine Ammer.

a chip on your shoulder

a strong and usually long-standing inclination to feel resentful or aggrieved, often about a particular thing; a sense of inferiority characterized by a quickness to take offence. informal
In 1830 the Long Island Telegraph described the practice which gave rise to this expression: ‘When two churlish boys were determined to fight, a chip would be placed on the shoulder of one, and the other demanded to knock it off at his peril’.
See also: chip, on, shoulder
Farlex Partner Idioms Dictionary

chip on (one's) shoulder

A habitually hostile or combative attitude.
See also: chip, on, shoulder
American Heritage® Dictionary of the English Language, Fifth Edition.
See also:
  • chip on one's shoulder
  • chip on shoulder
  • a chip on your shoulder
  • have a chip on (one's) shoulder
  • have a chip on your shoulder
  • have a quick temper
  • quick temper
  • short temper
  • be on a short fuse
  • have a short fuse