The Spanish word esquirol looks like the English word "squirrel," but it's not. The name for the animal is ardilla, which comes from an old Iberian language word. In Spanish, esquirol means "strikebreaker."
Here's how it happened: in Catalonia, in eastern Spain, the word in the Catalan language for the animal is esquirol, which comes from the Latin sciurus, which comes from the Greek skiouros. The English word shares the same root.
Toward the end of the 19th century, in a town near Barcelona named Santa Maria de Corcó, an inn had a pet squirrel in a cage at its entrance. Eventually the town began to be called "L'Esquirol" after the Inn of the Squirrel.
In 1902, 1908, and 1917, textile workers in the nearby towns went on strike, and workers from L'Esquirol offered to work in place of the strikers. So "strikebreaker" became esquirol — a term of disrespect, like scab in English.
That's how the Latin word for "squirrel" finally reached Spanish. But the term has no connection, except for a minor historical accident, with the cute little animal.
When words travel from one language to another, they don't always arrive safely.
— Sue Burke