'streamliner' originates from the English word 'streamline,' where 'stream' meant 'a continuous flow' and 'line' referred to 'a long, narrow mark or band.'

'streamline' transformed into 'streamliner' to specifically denote vehicles designed with reduced air resistance.

Initially, it referred to the design process of making objects more aerodynamic, but over time it evolved to specifically denote vehicles with such designs.