RER noun1 •A type of railway system that generally runs from suburbs or satellite towns into a city centre, with a central tunnel or overground corridor with higher speeds and more widely spread stations than a subway or metro.Reinvented according to this model—called regional express rail (RER)—Metra's key hubs would be O'Hare Airport, the Loop, and McCormick Place. — 2021 formsRERs
