'attitudinarianism' originates from English, formed by adding the suffix '-ism' to the adjective/noun 'attitudinarian', where 'attitudinarian' referred to a person given to adopting affected 'attitudes' or poses.

'attitudinarian' developed from the word 'attitude' (via French 'attitude' and Italian 'attitudine'), combined with the suffix '-arian' to denote a person characterized by that quality; the later English formation 'attitudinarianism' extended that to denote the doctrine, practice, or quality.

Initially it referred specifically to the behaviour or tendency of people who posed or affected manners ('the state of adopting attitudes'); over time it came to be used more broadly for affectedness or pretentious display of manner or attitude.