'everydayness' is a modern English formation combining 'everyday' + the abstract noun suffix '-ness'. 'everyday' itself is a compound of 'every' and 'day', and '-ness' is the productive suffix forming nouns meaning 'state or quality of'.

'every' originates from Old English elements (related to 'æfre' meaning 'ever'), and 'day' comes from Old English 'dæg'; these combined in Middle to Early Modern English as the compound 'everyday' meaning 'each day' or later 'ordinary'. The suffix '-ness' comes from Old English '-nes(s)e' and developed into the modern '-ness' used to form abstract nouns; adding it to 'everyday' produced 'everydayness' as a descriptive abstract noun in more recent usage (19th–20th century coinages and academic/literary contexts).

Originally 'every day' meant 'each day' (focusing on frequency). 'Everyday' as one word developed the meaning 'ordinary' or 'commonly used.' With '-ness' appended, the word's current sense is the 'quality of being ordinary' or 'the character of daily life'; the shift emphasizes abstract quality or the lived patterns of daily existence rather than mere frequency.