Earworm

Did you know that there's a word for that catchy tune you that you can't get out of your head? It's called an earworm! I found this definition -
“Earworm, a calque of the German Ohrwurm, is a term for a portion of a song or other musical material that becomes stuck in a person's head.”

This led me to wonder what a calque was! It seems it is an expression introduced into one language by translating it from another language.