'nonactivating' is formed from the prefix 'non-' (from Latin 'non', meaning 'not') plus 'activating', the present participle of 'activate' (from Latin 'activare').

'activate' comes from Latin 'activus' ('active') and Medieval/Latin 'activare'; the sense entered English via Late Latin and French forms into Middle English and became modern English 'activate', with the productive English prefix 'non-' attached to form 'nonactivating'.

Originally, the root 'activate' meant 'to make active' or 'to put into motion'; over time, combining with the negative prefix 'non-' produced the adjective meaning 'not causing activation', which is its current usage.