'nonreleasable' originates from English, specifically formed from the prefix 'non-' + the adjective 'releasable', where 'non-' meant 'not' and 'releasable' comes from 'release' + the suffix '-able'.

'releasable' developed from the verb 'release' (Middle English, influenced by Old French 'releser' / 'relaisser'), and 'nonreleasable' was formed in modern English by adding the negative prefix 'non-' to that adjective.

Initially, 'release' meant 'to let go or set free', and 'releasable' originally meant 'able to be set free'; over time the sense broadened to include 'able to be disclosed or made public', which is the basis for 'nonreleasable'.