'availer' originates from English, specifically the verb 'avail' combined with the agentive suffix '-er' to form an agent noun. The verb 'avail' ultimately comes from Old French 'valoir' and Latin 'valere', where 'valere' meant 'to be strong, to be worth'.

'avail' passed into Middle English from Old French (compare Old French 'avaloir'/'valoir'), derived from Latin 'valere'. The modern agent noun 'availer' is formed in English by adding the productive suffix '-er' to 'avail', and 'availers' is the regular plural.

Initially related to the Latin sense 'to be strong/ to be worth', the meaning shifted in English to 'to be of use, to help' (verb). The agent form came to mean 'one who uses something or benefits from it' (current sense).