- The secret publication and distribution of government-banned literature in the former Soviet Union.
- The literature produced by this system.
- An underground press.
- The <xref>secret</xref> <xref>copying</xref> and <xref>sharing</xref> of <xref>illegal</xref> publications, chiefly in the <xref>Soviet Union</xref>; <xref>underground</xref> publishing and its publications.
- A samizdat <xref>publication</xref>.
- a system of clandestine printing and distribution of dissident or banned literature