What is the meaning of Ultraleft?

Of or pertaining to ultraleftism.

Of a leftist movement or ideology: extreme and uncompromising; sectarian.

Extremely left-wing.

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.

The left communist tendency characterized by a synthesis of Dutch-German council communism and Italian left communism.

Italian left communism; Bordigism.

Leftism collectively considered uncompromising and sectarian, especially anti-Leninist Marxism.

An adherent of ultraleftism.

The most extreme ideologies of the political left.

Source: wiktionary.org