'nontypically' originates from Modern English, specifically formed from the prefix 'non-' plus the adverb 'typically', where 'non-' meant 'not' and 'typical' ultimately derives from Latin 'typicus' (from Greek 'typos') meaning 'of a type' or 'model'.

'nontypically' developed by attaching the negative prefix 'non-' to 'typical' (from Latin 'typicus', via Middle English/Old French influences) to form 'nontypical', and then adding the adverbial suffix '-ly' to produce the modern adverb 'nontypically'.

Initially the elements meant 'not' + 'of a type' (i.e. 'not typical'); over time this combined form has retained that sense and now specifically means 'in a manner that is not typical'.