certainty/ˋsɝtṇtI; ˈsɜːtnti/n plural certainties 1 [U] when you are completely sure about something 确定﹐确实: with certainty She knew with certainty that he was lying. 她肯定他在撒谎。2 [C] something that is definitely true or will definitely happen 确定[确实]的事﹔必然发生的事: The job losses aren’t a certainty. 裁员的事没有确定。