'nonmethodicalness' originates from Modern English, specifically formed from the negative prefix 'non-' (from Latin 'non' meaning 'not') + the adjective 'methodical' (from 'method') + the nominal suffix '-ness'.

'method' ultimately comes from Greek 'methodos' (μέθοδος), passed into Latin as 'methodus', then Old French 'methode' and Middle English 'method'; the adjective 'methodical' developed in Early Modern English, and the modern formation 'nonmethodicalness' is created by prefixing 'non-' and adding '-ness' to that adjective.

Originally 'method' referred to a 'way of pursuing' or 'pursuit' (Greek sense), later narrowing to 'systematic procedure'; consequently, 'nonmethodicalness' now denotes the absence of such system or systematic procedure.