noble metal vs silver

noble metal and silver both are nouns.

Word	Noun	Adjective	Verb	Adverb
noble metal	Yes	No	No	No
silver	Yes	Yes	Yes	No

As nouns, silver is a hyponym of noble metal; that is, silver is a word with a more specific, narrower meaning than noble metal:

noble metal: any metal that is resistant to corrosion or oxidation
silver: a soft white precious univalent metallic element having the highest electrical and thermal conductivity of any metal; occurs in argentite and in free form; used in coins and jewelry and tableware and photography

Other hyponyms of noble metal include atomic number 79, Au, gold, atomic number 78, platinum, Pt, Ag, atomic number 47.

noble metal (noun)	silver (noun)
any metal that is resistant to corrosion or oxidation	silverware eating utensils
	a trophy made of silver (or having the appearance of silver) that is usually awarded for winning second place in a competition
	a light shade of grey
	coins made of silver
	a soft white precious univalent metallic element having the highest electrical and thermal conductivity of any metal; occurs in argentite and in free form; used in coins and jewelry and tableware and photography

noble metal (adjective)	silver (adjective)
	of lustrous grey; covered with or tinged with the color of silver
	expressing yourself readily, clearly, effectively
	having the white lustrous sheen of silver
	made from or largely consisting of silver

noble metal (verb)	silver (verb)
	make silver in color
	turn silver
	coat with a layer of silver or a silver amalgam