get (one's) back up

1. To become angry, hostile, defensive, or irritable. John got his back up when his parents brought up the subject of college. My dad always gets his back up during election season. You're not in trouble or anything, so please don't get your back up. I'm just looking for information.

2. To cause one to become angry, hostile, defensive, or irritable. Election season always gets my dad's back up. Few things get my back up like hearing about a poacher killing an endangered animal. Why would you bring up tax reform around Uncle Ed? You know that gets his back up.

See also: back, get, up

get back up

To return to an upright or standing position, especially after having fallen or after having sat or lain down. I know you just sat down, but I'm afraid I'm going to have to ask you to get back up—those are not your seats. He's taken a beating tonight, and this might be it for the champ. No, wait, he's getting back up! I had a hard time getting back up after I slipped on the ice.

See also: back, get, up

get someone's back up

Also, get someone's dander up; put or set someone's back up . Make angry, as in Bill's arrogance really got my back up, or The foolish delays at the bank only put her back up. Get one's back up and get one's dander up mean "become angry," as in Martha is quick to get her dander up. The back in these phrases alludes to a cat arching its back when annoyed, and put and set were the earliest verbs used in this idiom, dating from the 1700s; get is more often heard today. The origin of dander, used since the early 1800s, is disputed; a likely theory is that it comes from the Dutch donder, for "thunder." Also see get someone's goat; raise one's hackles.

See also: back, get, up

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

get someone's back up

INFORMAL or

put someone's back up

BRITISH, INFORMAL

If someone or something gets your back up or puts your back up, they annoy you. What does get my back up is a girlfriend who gets jealous if someone else finds me attractive. I thought before I spoke again. The wrong question was going to get her back up. The appointment took the whole office by surprise and at first seemed to put people's backs up. Note: This expression may refer to the way cats raise their backs when they are angry.

See also: back, get, up

Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

get someone's back up

make someone annoyed or angry.

This phrase developed as an allusion to the way a cat arches its back when it is angry or threatened.

See also: back, get, up

get/put somebody’s ˈback up

make somebody annoyed: His silly remarks always get her back up.

This idiom refers to the way cats arch their backs when they are angry.

get someone's back up, to

To make someone angry. The expression alludes to the behavior of the domestic cat, which arches its back when it is attacked by a dog or is otherwise annoyed. This term began in the early eighteenth century as to put or set up the back. By 1864 it was, “He goes his own way . . . if you put his back up” (Sunday Magazine). See also get someone's dander up.