one's back is up

Definition

One is offended or angry.

Etymology

From the way a cat, when angry, raises or arches its back.

Example Sentences

• "My back is up, and I cannot hear the thought of wooing him any farther, nor would do it, though he were as pig a gentleman (look you) as Lucifer himself."
• "And I want you to be nice to Patty. For some reason her back is up."
• "Now my back is up. “Yes, the witch,” I hiss."