'avower' originates from English, specifically the word 'avow' plus the agentive suffix '-er'; 'avow' originates from Old French 'avouer,' ultimately from Late Latin 'advocare,' where 'ad-' meant 'to' and 'vocare' meant 'to call'.

'advocare' changed into Old French 'avouer' and Middle English 'avowen', and eventually became the modern English verb 'avow' and the agent noun 'avower'.

Initially it meant 'to call' in Latin; over time the sense shifted in Old French to 'acknowledge' or 'declare,' and in modern English 'avow' means 'to assert or confess'; consequently 'avower' means 'one who avows (declares or confesses)'.