Definition of "railfan"

A previewing railfan pointed out a mistake in the animation showing articulation.

1961, Augustus Wolfman, Photo Methods for Industry

From my own experience, I cannot say how one becomes a railfan […]

1975, Paul B Cors, Railroads

A number of US and Canadian book dealers regularly channel British titles to railfan collectors […]

1989, M Thomas Inge, Handbook of American Popular Culture