'assailable' originates from Latin, specifically the verb 'assalire' (from Classical Latin elements 'ad-' + 'salire'), where 'ad-' meant 'to' and 'salire' meant 'to leap, jump'.

'assailable' developed via Old French (verbs like 'assaillir' / 'assaillier') and Middle English (verbs such as 'assailen' / 'assail'), eventually forming the modern adjective 'assailable'.

Initially associated with the idea of 'to leap upon' or 'to attack', the sense shifted to 'to attack' generally and later to the adjectival meaning 'able to be attacked or criticized'.