Tat, also known as Caucasian Persian, Tat/Tati Persian, or Caucasian Tat, is a Southwestern Iranian language closely related to, but not fully mutually intelligible with Persian and spoken by the Tats in Azerbaijan and Russia. There is also an Iranian language called Judeo-Tat spoken by Mountain Jews.

The Tat people are an Iranian people presently living within Azerbaijan and Russia. The Tats are part of the indigenous peoples of Iranian origin in the Caucasus.