Lugha ya kirusi ni lugha ya kislavoni inayoongelewa kama lugha ya asili huko Urusi, Belarusi, Ukraine, Kazakhstan na Kyrgyzstan, na pia inatumika sana, ijapokuwa si kama lugha rasmi huko Latvia, Estonia na nchi nyingine nyingi zilizokuwa ni jamhuri katika Umoja wa Sovieti wa zamani.
The Russian language is a Slavic language spoken natively in Russia, Belarus, Ukraine, Kazakhstan and Kyrgyzstan, and is widely used, although without official imprimatur, in Latvia, Estonia and many other countries that form the constituent republics of the former Soviet Union.