1
the onset of [sth]
常指不愉快或严重事物的开始。
The onset of the rainy season caused flooding.
雨季的开始导致了洪水。
（尤指不愉快事情的）开始，开端
onsets — plural of onset
先理解核心含义，再看它在真实句子里的用法。
（尤指不愉快事情的）开始，开端
the beginning of something, especially something unpleasant
The onset of the rainy season caused flooding.
雨季的开始导致了洪水。
疾病或病症的初期阶段,症状开始显现。
The initial phase of a disease or condition, in which symptoms first become apparent.
音节的开头部分,位于音节核之前。
The initial portion of a syllable, preceding the syllable nucleus.
音符或其他声音的起始,振幅从零上升到初始峰值。
The beginning of a musical note or other sound, in which the amplitude rises from zero to an initial peak.
开始；开端。
A setting about; a beginning.
The onset of winter brought heavy snowfalls.
冬季的到来带来了大雪。
She experienced the sudden onset of a severe headache.
她突然开始剧烈头痛。
The onset of the economic crisis caused widespread panic.
经济危机的爆发引起了广泛的恐慌。
常指不愉快或严重事物的开始。
The onset of the rainy season caused flooding.
雨季的开始导致了洪水。
可省略of短语，但通常搭配of。
At the onset, symptoms are mild.
开始时，症状较轻。
强调伴随关系。
With the onset of economic crisis, unemployment rose.
随着经济危机的开始，失业率上升了。
Not this
The disease onset quickly.
Use this
The onset of the disease is quick.
“onset”是名词，不能用作动词。应使用“onset of + 名词”结构，或改用动词形式，如“The disease begins quickly.”。
Not this
The onset the war was sudden.
Use this
The onset of the war was sudden.
“onset”作“开始”解时，需后接介词“of”才能引出具体事物，缺少“of”会导致结构错误。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
在开始时
At the onset of the meeting, the chairman introduced the main topic.
在会议开始时，主席介绍了主要议题。
症状的出现
The onset of symptoms can be gradual or sudden.
症状的出现可以是逐渐的或突然的。
突然发作
The sudden onset of fever worried the parents.
突然发烧让父母很担心。
早发性
Early onset Alzheimer's disease is relatively rare.
早发性阿尔茨海默病相对罕见。
疾病发作
The patient experienced rapid onset of the disease after exposure.
患者在接触后迅速发病。
战争开始
The onset of war brought chaos and destruction.
战争的开始带来了混乱和破坏。
在...开始时
At the onset of the meeting, she introduced the agenda.
在会议开始时，她介绍了议程。
早发型
He was diagnosed with early onset Alzheimer's disease.
他被诊断出患有早发型阿尔茨海默病。
随着...的开始
With the onset of winter, temperatures dropped significantly.
随着冬季的到来，气温显著下降。
Use onsets naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
把"onset"拆成"on"（在）和"set"（设置），联想"开始设置"，形象记住"开始、开端"的含义。
formal
Words ending in '-set' share the same spelling cluster. Note that while 'set', 'reset', and 'upset' are stressed on the second syllable, 'sunset', 'offset', and 'outset' are stressed on the first syllable. Of these, only 'offset' has the same stressed vowel /ɒ/ as 'onset', but its coda differs (/f/ vs /n/).
Dictionary facts from ECDICT, WIKTIONARY, WORDNET.