'nonperiodically' originates from English, formed by the negative prefix 'non-' + the adjective 'periodic' + the adverbial suffix '-ally', where 'non-' meant 'not' and 'periodic' comes from words meaning 'recurring at intervals'.

'periodic' came into English via Latin and French from Greek 'periodos' (from 'peri-' meaning 'around' + 'hodos' meaning 'way'); 'periodic' gave rise to 'periodically', and the modern adverb 'nonperiodically' was formed by adding the prefix 'non-'.

Initially related words meant 'occurring at intervals' (from Greek roots), and 'nonperiodically' has meant 'in a manner not occurring at regular intervals' since its formation in modern English, retaining that negated sense.