The word комисса́р is used in Russian for both political and administrative officials. The title has been used in the Soviet Union and Russia since the time of Peter the Great.
Commissaries were used during the Provisional Government (March–July 1917) for regional heads of administration, but the term commissar is associated with a number of Cheka and military functions in Bolshevik and Soviet government military forces during the Russian Civil War (the White Army widely used the collective term "bolsheviks and commissars" for their opponents) and with the later terms People's Commissar (or narkom) for government ministers and political commissar in the military.
A People's Commissar (informally abbreviated narkom) was a government official serving in a Council of People's Commissars. This title was first used by the Russian SFSR (out of dislike for the tsarist and bourgeois term minister) and then copied among the many Soviet and Bolshevik-controlled states in the Russian Civil War.
The government departments headed by a People's Commissar were called People's Commissariat (informally abbreviated narkomat).
People's Commissars and People's Commissariats were renamed Ministers and Ministries in 1946 by a decree of the Supreme Soviet of the Soviet Union.