Free-reed instrument and Mouth harp

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

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

Mouth harp noun - A small rectangular free-reed instrument having a row of free reeds set back in air holes and played by blowing into the desired hole.

Free-reed instrument and mouth harp are semantically related. Sometimes you can use "Free-reed instrument" instead a noun phrase "Mouth harp".