'nonassignability' originates from English, specifically formed from the prefix 'non-' + 'assignability', where 'non-' meant 'not' and 'assignability' is derived from 'assign' + '-ability' meaning 'capability of being assigned'.

'nonassignability' was created in Modern English by compounding 'non-' with 'assignability'. 'Assignability' itself derives from the verb 'assign', which came into English via Old French 'assigner' (from Latin 'assignare'). Over time 'assign' acquired the legal sense 'to transfer (rights or property)'; the suffix '-ability' was added in later English to form 'assignability'.

Initially, 'assign' originally had senses related to marking or allotting (from Latin roots), but over time it evolved to include the legal sense 'to transfer a right or duty'; 'nonassignability' therefore came to mean 'not capable of being transferred or assigned' in modern usage.