nipple shield vs shield

nipple shield and shield both are nouns.

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

As nouns, shield is a hypernym of nipple shield; that is, shield is a word with a broader meaning than nipple shield:

nipple shield: a rubber or plastic shield to protect the nipples of nursing women
shield: a protective covering or structure

nipple shield (noun)	shield (noun)
a rubber or plastic shield to protect the nipples of nursing women	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

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