Definition of "semantron" []

• A percussion instrument used chiefly in Eastern Orthodox monasteries to summon the brethren to prayer or to lead processions. (noun)

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• "At the west end of the courtyard, a semicircular base may mark the location of a semantron, a resonant plank struck to call the monks to prayer."
• "On the other hand, semantron, used to announce the beginning of service in Greek monasteries, was a flat plate of metal and its name (from semainein, "to make a signal") is obviously the counterpart of signum."
• "Just then, the semantron awoke the priest for the night services."