point source vs rootage

point source and rootage both are nouns.

Word	Noun	Adjective	Verb	Adverb
point source	Yes	No	No	No
rootage	Yes	No	No	No

As nouns, rootage is a hypernym of point source; that is, rootage is a word with a broader meaning than point source:

point source: a concentrated source (especially of radiation or pollution) that is spatially constricted
rootage: the place where something begins, where it springs into being

Other hypernyms of point source include beginning, origin, root, source.

point source (noun)	rootage (noun)
a concentrated source (especially of radiation or pollution) that is spatially constricted	the place where something begins, where it springs into being
	a developed system of roots
	fixedness by or as if by roots