ICAO definitions are
ATZ An aerodrome traffic zone is an airspace of defined dimensions established around as aerodrome for the protection of aerodrome traffic
CTA A control area is a controlled airspace extending upwards from a specified limit above the earth
CTR A control zone is a controlled airspace extending upwards from the surface of the earth to a specified upper limit.
TMA A terminal control area is an area normally established at the confluence of ATS routes in the vicinity of one or more major aerodromes
So basically a TMA is a large shared CTA which connects to lots of airways. The airspace classification is independent of the airspace type.
Or at least, that's how I've always understood it.