Teletype is a term used to describe a machine that sends or receives typed messages using a telegraph system. There are several synonyms for this term, including teleprinter, ticker, and telex machine. A teleprinter refers to an electromechanical machine that receives and sends printed messages via a communication network. A ticker is a machine that prints out financial information, such as stock market quotes, in real-time. Lastly, a telex machine is a device that functions similar to a teleprinter but is capable of sending and receiving transmissions across the world. All these words are commonly used in the field of communication and technology, and they depict different types of devices that enable the transmission of information over distance.