The story
From the way a cat, when angry, raises or arches its back.
Etymology from Wiktionary, CC BY-SA 4.0.
one's back is up
Today it means: One is offended or angry. Full definition →
Today it means: One is offended or angry. Full definition →
From the way a cat, when angry, raises or arches its back.
Etymology from Wiktionary, CC BY-SA 4.0.