'arraignableness' is formed from the adjective 'arraignable' (able to be arraigned), itself built from the verb 'arraign' plus the suffixes '-able' and '-ness'. 'Arraign' originates from Anglo-Norman/Old French, specifically from a word like 'areignier' or similar Old French forms derived from Latin elements meaning 'to call' or 'to bring to account'.

'Arraign' passed into Middle English from Old French (Anglo-Norman) as forms such as 'areinen'/'areignen' and eventually became the modern English 'arraign'; the adjective 'arraignable' and the noun-forming suffix '-ness' produced 'arraignableness'.

Initially associated with the act of calling someone to answer before a court (the older senses focused on summoning and presenting), it has retained that core legal sense and now denotes the state of being subject to that process ('able to be arraigned').