in that case, why it is called 'brutalism' instead of 'brutism' ? I'm not implying you are wrong, but probably it's the reason of confusion:
* brutal - brutalism
* brut - brutism
* brutal - brutalism
* brut - brutism
> The term Nybrutalism (New Brutalism)[16] was coined by the Swedish architect Hans Asplund to describe Villa Göth, a modern brick home in Uppsala, designed in January 1950[9] by his contemporaries Bengt Edman and Lennart Holm.[10]
* https://en.wikipedia.org/wiki/Brutalist_architecture#History
> Asplund's neologism caught on in Stockholm and was picked up by British architectural pilgrims to that city, among them Oliver Cox, Graeme Shankland and Michael Ventris, the decoder of Linear B (an ancient script seen as one of the great linguistic riddles). Although the epithet signified nothing, or maybe because it signified nothing, it was taken up as a slogan of defiance or something by arty young British architects, none artier than Alison and Peter Smithson and their representative on Earth, Reyner Banham, an architectural critic whose prose may cause all but the entirely insentient to wince.
* https://www.theguardian.com/artanddesign/2014/feb/13/jonatha...
Or Reyner Banham why he chose that name in his 1955 essay:
> They have created the idea of a Modern Movement – this was known even before Basil Taylor took up arms against false historicism – and beyond that they have offered a rough classification of the ‘isms’ which are the thumb-print of Modernity into two main types: One, like Cubism, is a label, a recognition tag, applied by critics and historians to a body of work which appears to have certain consistent principles running through it, whatever the relationship of the artists; the other, like Futurism, is a banner, a slogan, a policy consciously adopted by a group of artists, whatever the apparent similarity or dissimilarity of their products. And it is entirely characteristic of the New Brutalism – our first native art-movement since the New Art-History arrived here-that it should confound these categories and belong to both at once.
* https://www.architectural-review.com/archive/the-new-brutali...
It opens with an epigraph by Le Corbusier:
> L’Architecture, c’est, avec des matières bruts, ètablir des rapports émouvants’rnouvants.
(Architecture is, with raw materials, establishing moving and moving relationships.)
See also:
The word brutal comes from Medieval Latin brutalis ("savage, stupid"), from Latin brūtus ("dull, stupid"). The English use of the word has a particular connotation/definition that differs from both the French and original Latin.
The French word brut comes from Middle French, from Old French, from the Latin brūtus (“heavy, dull”). Today it means either "raw", "strong", or "gross" ("big, thick, large, stout", "whole, entire, overall, total, aggregate").
The word brutalism could translate as "a system, belief, or artistic movement, of or relating to, a whole/entire, dull/big/thick stupid/savage aggregate". Doesn't make for a great definition.
However, that's not the whole story.
The word brutalism was coined first by Swedish architect Hans Asplund in 1950 as nybrutalism. It described a home Villa Göth (built by Bengt Edman and Lennart Holm) made using red brick - not concrete. In 1955, British journalist Reyner Banham popularized an essay called “The New Brutalism,” in which he used the brick-and-steel Hunstanton School (by architects Peter and Alison Smithson) as an example of this new form. The point was to stretch Modernism even further, but concrete was not (yet) involved.
In 1966, in French architectural critic Reyner Banham's book "The New Brutalism: Ethic or Aesthetic?", he redefined the word by suggesting that brut was a French pun, combining the meanings of "béton brut" and "brutal". 16 years after the coining of nybrutalism, the term's use became linked to concrete.
So really, the word originated as a reference to the the raw edges of an extended Modernist design, and then was reinterpreted as a pun relating to raw concrete, and then the English who weren't aware of this pun simply assumed it related to the brutality of the buildings' aesthetics.
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ps. brutism would (without a different explicit definition, use, or origin) be the same word as brutaism, just without the "of or pertaining to" postfix. English has thousands of words which have different spellings and the same meaning. You can replace the -al postfix with -ition or -ision and it means the same thing (disposition/disposal=dispose, proposition/proposal=propose, submission/submittal=submit, transmission/transmittal=transmit). But not in all cases, as some forms end up having a different origin (reversion/reversal=revert,reverse).