[noun] the back part a 横笛(yokobue, “Japanese transverse flute”), about one centimeter from the embouchure hole, usually shaped like a cicada (Can we verify(+) this sense?)
[noun] a small pulley used to raise objects to high places
[noun](by extension) a pulley used to lift sails in a 和船(wasen, “Japanese-style ship”)(Can we verify(+) this sense?)
(This term, セミ(semi), is the katakana spelling of the above term.)