semaphore
n//ˈsɛm.əˌfoɹ//semafor, semaforera
(programming) A bit, token, fragment of code, or some other mechanism which is used to restrict access to a shared function or device to a single process at a time, or to synchronize and coordinate events in different processes.
(ambitransitive, figurative) To signal using, or as if using, a semaphore, with the implication that it is done nonverbally.