'annualness' originates from Modern English, specifically formed from the adjective 'annual' with the suffix '-ness' to indicate a state or quality; 'annual' itself derives from Latin 'annuus' (from 'annus' meaning 'year').

'annual' changed from Latin 'annuus' into Old French/Anglo-French forms (e.g. 'annuel') and Middle English (e.g. 'anuel'), eventually becoming modern English 'annual'; the abstract noun 'annualness' is a later Modern English formation using the productive suffix '-ness'.

Initially 'annuus' meant 'yearly' in Latin; over time the core idea of 'yearly' remained, and the suffix '-ness' added an abstract noun sense meaning 'the state/quality of being yearly'.