class Arachnida vs arachnoid

class Arachnida and arachnoid both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Arachnida	Yes	No	No	No
arachnoid	Yes	Yes	No	No

class Arachnida (noun)	arachnoid (noun)
a large class of arthropods including spiders and ticks and scorpions and daddy longlegs; have four pairs of walking legs and no wings	air-breathing arthropods characterized by simple eyes and four pairs of legs
	the middle of the 3 meninges

class Arachnida (adjective)	arachnoid (adjective)
	relating to or resembling a member of the class Arachnida