[countable] (plural standbys) a thing or person that can always be used if needed, for example if sth/sb else is not available or if there is an emergency后备人员；备用品◆I have a laptop as a standby in case my computer crashes.万一我的计算机崩溃了，我另外还有一台膝上型电脑备用。 ●on ˈstandbyready to do sth immediately if needed or asked待命◆We are on standby to increase production if demand increases.如果需求增长我们随时准备增加产量。ready to travel if a ticket becomes available一旦有票随时准备出发  ➡  idiom at fly