austral vs southern

austral is a noun but southern is not a noun.

Word	Noun	Adjective	Verb	Adverb
austral	Yes	Yes	No	No
southern	No	Yes	No	No

austral (noun)	southern (noun)
the basic unit of money in Argentina; equal to 100 centavos

austral (adjective)	southern (adjective)
of the south or coming from the south	situated in or coming from regions of the south
	in or characteristic of a region of the United States south of (approximately) the Mason-Dixon line
	from the south; used especially of wind
	situated in or oriented toward the south