sulphurous vs acid

sulphurous is not a noun while acid is a noun.

Word	Noun	Adjective	Verb	Adverb
sulphurous	No	Yes	No	No
acid	Yes	Yes	No	No

As adjectives, sulphurous and acid are synonyms defined as:

Other synonyms of sulphurous include acerb, acerbic, acrid, bitter, blistering, caustic, sulfurous, virulent, vitriolic.

sulphurous (noun)	acid (noun)
	street name for lysergic acid diethylamide
	any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt

sulphurous (adjective)	acid (adjective)
of or related to or containing sulfur or derived from sulfur	having the characteristics of an acid
characterized by oppressive heat and humidity	being sour to the taste
harsh or corrosive in tone	harsh or corrosive in tone