The Collaborative International Dictionary
Sematrope
Sematrope \Sem"a*trope\, n. [Gr. sh^ma sign + tre`pein to turn.
]
An instrument for signaling by reflecting the rays of the sun
in different directions.
--Knight.
Wiktionary
sematrope
n. (context dated English) An instrument for signalling by reflecting the rays of the sun in different directions.