ultraleft

adj

1. Of or pertaining to ultraleftism.

   “This rejection of anything connected with bourgeois democracy would later become associated mainly with ultraleft radicalism, but its beginnings were another matter.”

2. (derogatory)Of a leftist movement or ideology: extreme and uncompromising; sectarian.
3. Extremely left-wing.

noun

1. (collective, uncountable, usually)The strain or strains of leftism often associated with left communism, which practice rejection of both social democracy and state socialism as well as opposition to Leninism; i.e, ultraleftism.
2. (uncountable, usually)The left communist tendency characterized by a synthesis of Dutch-German council communism and Italian left communism.
3. (broadly, uncountable, usually)Italian left communism; Bordigism.
4. (derogatory, uncountable, usually)Leftism collectively considered uncompromising and sectarian, especially anti-Leninist Marxism.
5. (countable, rare, usually)An adherent of ultraleftism.
6. (uncountable, usually)The most extreme ideologies of the political left.