Käi (gender unknown)
From "käi" [grindstone] ?; Named after the sound of it, when grinding?
Leydi, Roberto: La zampogna in Europa. Como, 1979, p.115.
Tonurist [sic], Igor [Tõnurist]: The Estonian bagpipe. In: The bagpipes in Europe, 1 (1976), p.49.