soundboard vs piano

soundboard and piano both are nouns.

Word	Noun	Adjective	Verb	Adverb
soundboard	Yes	No	No	No
piano	Yes	Yes	No	Yes

soundboard (noun)	piano (noun)
(music) resonator consisting of a thin board whose vibrations reinforce the sound of the instrument	a keyboard instrument that is played by depressing keys that cause hammers to strike tuned strings and produce sounds
	(music) low loudness

soundboard (adjective)	piano (adjective)
	(used chiefly as a direction or description in music) soft; in a quiet, subdued tone

soundboard (adverb)	piano (adverb)
	used as a direction in music; to be played relatively softly