the amount of time that is given to a particular subject, or to an advertisement, on radio or television （广播、电视节目或广告的）播出时间
the amount of time that a mobile phone/cellphone is used in a particular period of time for sending or receiving calls that you usually pay for （使用移动电话时需要缴费的）通话时间◆This deal gives you 180 minutes free airtime a month. 这项协议允许你每月免费通话 180 分钟。