'barker' originates from English, specifically from the verb 'bark' with the agentive suffix '-er', where 'bark' was originally an imitative word for the sharp cry a dog or similar animal makes.

'barker' developed in Early Modern English from the base verb 'bark' (Old English and Middle English forms of 'bark' existed as imitative terms), with the agent suffix '-er' forming a noun meaning 'one who barks' and later applied metaphorically to human advertisers and promoters.

Initially, it could refer literally to something that barks (an animal) or figuratively to someone who makes loud noises; over time it came to be used especially for people who loudly advertise or promote shows and attractions.