Extremism, especially in politics or government; radicalism.

ul′tra·ist n.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
References in classic literature ?
His attention must be commanded by the signs that the Church, or religious party, is falling from the Church nominal, and is appearing in temperance and non-resistance societies; in movements of abolitionists and of socialists; and in very significant assemblies called Sabbath and Bible Conventions; composed of ultraists, of seekers, of all the soul of the soldiery of dissent, and meeting to call in question the authority of the Sabbath, of the priesthood, and of the Church.
She covers actual infinities: Cantor's proofs and modern fiction, Jorge Luis Borges and the measure of prose supplanting the symbol for the thing itself: Borges' ultraist beginnings, the lemniscate: infinite shapes in te work of Samuel Beckett, and one: J.
Whitman's powerful verse, vision, and persona also have something in them that provokes and inspires, that speaks globally to readers and writers, sending them, as Ultraist Eugenio Montes put it in 1919, "fervid impulses from the son of Long Island." (35)
Hidden behind a masculine pseudonym and wary of the frenetic modernity celebrated by her Ultraist colleagues, she seems to have been aware of her exile from the joys of a very masculine, even sexist, avant-garde.
The first chapter is devoted to Spanish Ultraist poetry (1919-1923) and each following chapter concerns a specific artistic movement that developed visual poetry and elevated it to different dimensions.
Since the ultraist polemical slant of this revised piece has previously been discussed elsewhere, I will here focus on Borges's adaptation of, and particularly deviations from, his source.
(16.) The most ultraist being Conor Cruise O'Brien (1996).
As Georgie gradually inserted himself into Madrid's literary scene, he and his sister came to know Guillermo de Torre, an activist poet, critic, editor, and collector of intellectual ephemera, in 1920, de Torte issued as a broadsheet his so-called Manifiesto ultraista vertical to which Norah contributed a print of a bicyclist, perhaps to suggest the futurist direction of the Ultraist movement.
His innovativeness earns Vallejo a place alongside the other authors mentioned here: owing little to cubist, dadaist, or ultraist influences, he crafts a satisfying language all his own that defies imitation.
When Xirgu's production of Mariana Pineda opened that fall in Madrid, Lorca told a reporter from the Heraldo de Madrid that he was neither an ultraist "nor a member of the avant-garde." His poetic roots lay with Gongora, he said; his the-atrical wellspring was Lope de Vega.