onset [ˈɒnset]

以下由轻松背单词网站提供

n.进攻，袭击，开始，突然开始

the moment at which something unpleasant begins

The drug must be taken from the onset of the infection. 这种药必须在感染的最初期就开始服用。
Our troops withstood the onset of the enemy. 我们的部队抵挡住了敌人的进攻。