If someone or something is on standby, they are ready to be used if they are needed.
例句
Five ambulances are on standby at the port...5 辆救护车在港口待命。Security forces have been put on standby in case of violence.安全部队已处于待命状态,以防出现暴力事件。
ADJ
(戏票或机票)最后时刻廉价出售的,剩余的
A standby ticket for something such as the theatre or a plane journey is a cheap ticket that you buy just before the performance starts or the plane takes off, if there are still some seats left.
例句
Access International books standby flights from New York to Europe.全球通达公司可以预订从纽约到欧洲的剩余机票。