1 [U] the number of times sth happens in a particular period 频率（在特定时间内某种事情发生的次数）: Fatal accidents have decreased in frequency in recent years. 近几年死亡事故发生的频率已经下降。

2 [U] the fact that sth happens often 频繁: The frequency of child deaths from cancer near the nuclear power station is being investigated. 在核电厂附近地区，经常有儿童死于癌症，有关当局对这个现象正在进行调查。

3 [C,U] the rate at which a sound wave or radio wave moves up and down (vibrates) 频率（声波或无线电波振动的次数）: high-frequency/low-frequency sounds 高╱低频声 ☞picture at wavelength 见wavelength插图