red rag

American  

noun

1. something that arouses anger; a provocation; red flag.

   A mere mention of the incident is a red rag to him.

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red rag British  

noun

1. a provocation; something that infuriates

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Etymology

Origin of red rag

First recorded in 1690–1700

Example Sentences

That was like a "red rag to a bull" he said, and he went on to get a degree in animal nutrition and to set up a farm in Bedfordshire.

From BBC

Then he grabs a faded red rag from a cardboard box next to the sink, tips the can, and wets it.

From Literature

Fairclough added wearing number one "was like waving a red rag to a bull at that level of football".

From BBC

"That was a red rag to a bull" she explains.

From BBC

Barely a week after a 6-0 humbling at Chelsea they were a team transformed, the sight of Liverpool like a red rag to a bull.

From BBC