IATA codes

The meanings of some IATA codes are obvious (MAN, LHR, MIA for example) and some are not. A couple that are not are Chicago O’Hare (ORD – because it was formally known as Orchard Field) and Columbus OH (CMH – Columbus Maintenance Hangar!).

Does anyone know the meanings of some of the other less-obvious USA ones, Washington Dulles (IAD) and Cincinnati (CVG) especially appreciated?

Many thanks
Mike