piano action vs piano

piano action and piano both are nouns.

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

piano action (noun)	piano (noun)
action consisting of a system of levers that move a felt hammer to strike the strings when a key is depressed	a keyboard instrument that is played by depressing keys that cause hammers to strike tuned strings and produce sounds
	(music) low loudness

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

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