dérater

An old-fashioned/technical verb meaning to remove an animal's spleen — now mostly replaced by splénectomiser in veterinary language. It survives mainly through the idiom courir comme un dératé, "to run like the wind," from the old belief that removing a dog's spleen made it run faster.

• Le vétérinaire a dû dérater le chien après l'accident. — The vet had to remove the dog's spleen after the accident.
• Cette procédure pour dérater un animal est aujourd'hui rarement pratiquée. — This procedure for removing an animal's spleen is rarely performed today.
• Il a couru comme un dératé pour attraper le bus. — He ran like the wind to catch the bus.

The finite verb itself is dated/technical — most French speakers only know this root through the fixed expression courir comme un dératé, not the verb dérater on its own.

• expression Courir comme un dératé — A fixed expression meaning "to run extremely fast," rooted in the old (mistaken) belief that a dog with its spleen removed would run faster — confirmed by CNRTL and other standard French dictionaries.