From Sanskrit *sthandila* (cool ground), via Prakrit *thaṃḍa*. The retroflex consonants (ठ, ड) are characteristic of native Indo-Aryan vocabulary inherited through Prakrit rather than borrowed from Sanskrit or Persian.

*ठंडा* does double duty in Indian English and Hindi slang: "Thanda lo!" ("Have a cold drink!") is a classic street-vendor call, and Coca-Cola once ran a famous Indian campaign with the slogan *"Thanda matlab Coca-Cola"* ("Cold means Coca-Cola"). Beyond temperature, calling someone *ठंडा* can mean they are emotionally reserved or unfazed — similar to saying someone is "cool as a cucumber" in English.