A signaling device is a tool used to communicate information or instructions. The three crossword solutions for the term signaling device are semaphore, SIREN, and SENSOR. Semaphore is a system of visual communication using flags or lights held in predetermined positions. A SIREN is an auditory signaling device that produces a loud sound as a warning or alert. Lastly, a SENSOR is an electronic device that detects and responds to some type of input from the physical environment.