
1) Plotter against Nikolai I
Found on
https://www.crosswordclues.com/clue/decembrist

• (n.) One of those who conspired for constitutional government against the Emperor Nicholas on his accession to the throne at the death of Alexander I., in December, 1825; -- called also Dekabrist.
Found on
http://thinkexist.com/dictionary/meaning/decembrist/

any of the Russian revolutionaries who led an unsuccessful uprising on Dec. 14 (Dec. 26, New Style), 1825, and through their martyrdom provided a ... [15 related articles]
Found on
http://www.britannica.com/eb/a-z/d/22

Member of one of several Russian secret societies which adopted western liberal ideas and joined forces to attempt a rebellion against the new Tsar Nicholas I in December 1825. The rebellion was...
Found on
http://www.encyclo.co.uk/local/20688
De·cem'brist noun (Russian Hist.) One of those who conspired for constitutional government against the Emperor Nicholas on his accession to the throne at the death of Alexander I., in December, 1825; -- called also
Dekabrist . « He recalls the history of the
decembrists . . ....
Found on
http://www.encyclo.co.uk/webster/D/15

a participant in the conspiracy and insurrection against Nicholas I on his accession in December, 1825.
Found on
https://www.infoplease.com/dictionary/decembrist
No exact match found.