'attitudinise' originates from English formation combining the noun 'attitude' with the verb-forming suffix '-ise' (from French '-iser' and ultimately from Greek/Latin formative elements), where 'attitude' meant 'posture; manner'.

'attitude' entered English from French 'attitude', itself from Italian 'attitudine' and ultimately from Latin 'aptitudo' (from 'aptus'); the verb 'attitudinize/attitudinise' was formed in English in the late 19th century by adding the productive suffix '-ize/-ise' to 'attitude'.

Initially it meant 'to assume a physical posture or bearing', but over time it came to mean more specifically 'to adopt an affected or ostentatious manner or pose for effect.'