'yearliness' originates from English, specifically the word 'yearly' combined with the suffix '-ness', where '-ness' meant 'state or quality'.

'yearliness' developed from the adjective 'yearly' plus the noun-forming suffix '-ness'. 'Yearly' itself comes from Old English 'gēarlīċ' (from 'gēar' meaning 'year' + the suffix '-līċ' meaning 'like' or 'pertaining to'), which evolved into Middle English forms and then modern English 'yearly'.

Initially it signified something 'pertaining to a year' (via 'yearly'); over time it came to mean specifically 'the state or quality of being yearly' (annuality).