Free-reed instrument and Piano accordion

Free-reed instrument noun - A wind instrument with a free reed.

Piano accordion and free-reed instrument are semantically related. In some cases you can replace phrase "Piano accordion" with "Free-reed instrument", this phrases are similar.

Piano accordion noun - A portable box-shaped free-reed instrument; the reeds are made to vibrate by air from the bellows controlled by the player.

Free-reed instrument and piano accordion are semantically related. You can use "Free-reed instrument" instead a noun phrase "Piano accordion".