n.[theS][(+of)]

1. 開始
   He went to see a doctor at the onset of a fever.

   他開始發燒時便去看醫生了。

2. 攻擊，襲擊
   Our troops withstood the onset of the enemy.

   我們的部隊抵擋住了敵人的進攻。

n.

1. the beginning of something, especially something unpleasant.
2. archaic a military attack.