Relays are commonly defined as devices that act as switches, allowing an electrical current to pass through a certain circuit. However, there are several different words which can be used as synonyms for this term. One common synonym is the word "transmitters," which refers to devices that are used to send signals or messages over a distance. Other synonyms for relays include "switches," "controllers," "actuators," "converters," and "converters." Each of these words can be used to denote a device or system that plays a similar role to a relay, allowing some type of message or energy to be transmitted from one point to another.