Meaning of SEMAPHORE in English

SEMAPHORE

[noun] [U] - a system of communication using two mechanical arms or hand-held flags which are moved into different positions to represent different letters, numbers or symbolsSemaphore was widely used at sea, before the advent of electricity.(figurative) When I lived opposite her we would send semaphore signals (= messages without speaking) to each other from our bedroom windows.

Cambridge English vocab.      Кембриджский английский словарь.