subbotnik
/suːˈbɒtnɪk/Russian History
noun
In the Soviet Union: a day, typically a Saturday, worked without pay for the benefit of the collective.
- The practice originated with workers on the Moscow-Kazan railway in Moscow on 10 May 1919..
Origin
1920s (in an earlier sense). From Russian subbotnik a day, typically a Saturday, worked without pay for the benefit of the collective from subbota Saturday + -nik.