Transcaucasia vs Caucasus

Transcaucasia and Caucasus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Transcaucasia	Yes	No	No	No
Caucasus	Yes	No	No	No

Transcaucasia (noun)	Caucasus (noun)
a geographical region to the south of the Caucasus Mountains and to the north of Turkey that comprises Georgia and Armenia and Azerbaijan	a large region between the Black and Caspian seas that contains the Caucasus Mountains; oil is its major resource
	the mountain range in Caucasia between the Black Sea and the Caspian Sea that forms part of the traditional border between Europe and Asia