'irateness' originates from modern English, formed by adding the suffix '-ness' to the adjective 'irate', which ultimately comes from Latin 'iratus', where 'ira' meant 'anger'.

'irateness' was formed in English by attaching '-ness' to 'irate' (Modern English); 'irate' entered English in the early 17th century from Latin 'iratus' (via or alongside French), which derived from Latin 'ira'.

Initially the Latin root 'ira' meant 'anger', and the adjective 'irate' meant 'angry'; over time the noun 'irateness' came to mean 'the state or quality of being angry'.