carapace vs shield

carapace and shield both are nouns.

Word	Noun	Adjective	Verb	Adverb
carapace	Yes	No	No	No
shield	Yes	No	Yes	No

As nouns, carapace and shield are synonyms defined as:

carapace and shield: hard outer covering or case of certain organisms such as arthropods and turtles

Other synonyms of carapace include cuticle, shell.

carapace (noun)	shield (noun)
hard outer covering or case of certain organisms such as arthropods and turtles	hard outer covering or case of certain organisms such as arthropods and turtles
	armor carried on the arm to intercept blows
	a protective covering or structure

carapace (verb)	shield (verb)
	protect, hide, or conceal from danger or harm
	hold back a thought or feeling about