negro vs coloured

negro is not a noun while coloured is a noun.

Word	Noun	Adjective	Verb	Adverb
negro	No	Yes	No	No
coloured	Yes	Yes	No	No

As adjectives, negro and coloured are synonyms defined as:

Other synonyms of negro include colored.

negro (noun)	coloured (noun)
	a United States term for Blacks that is now considered offensive

negro (adjective)	coloured (adjective)
having skin rich in melanin pigments;	having color or a certain color; sometimes used in combination
	(used of color) artificially produced; not natural
	having skin rich in melanin pigments;
	favoring one person or side over another