a system that allows someone to watch on a television screen what is happening in different parts of a building, town etc. The abbreviation CCTV is often used instead of the full word. 闭路电视(常用缩略词CCTV来代替)
a communication system in a radio or television studio that allows people to speak to each other without the audience hearing what they say 对讲系统(广播电台或电视演播室内使用的一种通讯系统,观众听不到讲话的内容)