firebrick vs brick

firebrick and brick both are nouns.

Word	Noun	Adjective	Verb	Adverb
firebrick	Yes	No	No	No
brick	Yes	No	Yes	No

As nouns, brick is a hypernym of firebrick; that is, brick is a word with a broader meaning than firebrick:

firebrick: brick made of fire clay; used for lining e.g. furnaces and chimneys
brick: rectangular block of clay baked by the sun or in a kiln; used as a building or paving material

firebrick (noun)	brick (noun)
brick made of fire clay; used for lining e.g. furnaces and chimneys	rectangular block of clay baked by the sun or in a kiln; used as a building or paving material
	a good fellow; helpful and trustworthy

firebrick (verb)	brick (verb)
	To stop working (of an electronic device)