rotund vs fat

rotund is not a noun while fat is a noun.

Word	Noun	Adjective	Verb	Adverb
rotund	No	Yes	No	No
fat	Yes	Yes	Yes	No

rotund (noun)	fat (noun)
	excess bodily weight
	a kind of body tissue containing stored fat that serves as a source of energy; it also cushions and insulates vital organs
	a soft greasy substance occurring in organic tissue and consisting of a mixture of lipids (mostly triglycerides)

rotund (adjective)	fat (adjective)
excessively fat	having an (over)abundance of flesh
(of sounds) full and rich	containing or composed of fat
spherical in shape	marked by great fruitfulness
	lucrative
	having a relatively large diameter

rotund (verb)	fat (verb)
	make fat or plump