phylum Arthropoda vs class Tardigrada

phylum Arthropoda and class Tardigrada both are nouns.

Word	Noun	Adjective	Verb	Adverb
phylum Arthropoda	Yes	No	No	No
class Tardigrada	Yes	No	No	No

phylum Arthropoda (noun)	class Tardigrada (noun)
jointed-foot invertebrates: arachnids, crustaceans, insects, millipedes, centipedes	in some classifications considered a separate phylum: microscopic arachnid-like invertebrates living in water or damp moss having 4 pairs of legs and instead of a mouth a pair of stylets or needlelike piercing organs connected with the pharynx