'apocryphalness' originates from Late Latin and Greek, specifically from the Late Latin/Medieval Latin adjective 'apocryphalis' (from Greek 'apokryphos'), where 'apo-' meant 'away' and 'kryphos' meant 'hidden'.

'apocryphalness' changed via Late Latin/Medieval Latin 'apocryphalis' (from Greek 'apokryphos') into the English adjective 'apocryphal'; the noun 'apocryphalness' was formed later by adding the suffix '-ness' to express the state or quality.

Initially it meant 'hidden' or 'secret' (from Greek 'apokryphos'), but over time the sense shifted to 'of doubtful authenticity; spurious', which is the modern primary meaning.