A sensation, almost of faintness, had seized upon him.是什么意思？

A sensation, almost of faintness, had seized upon him.

一阵难受的感觉袭上心头,他简直要晕过去了.

sensation

n. 感觉，直觉，知觉，轰动；

例句
...a physical sensation of being bathed in love.
坠入爱河的生理快感

almost

adv. 几乎，差不多，将近，快要，近乎；

例句
Despite considerable pain she has been getting out and about almost as normal...
尽管还很痛，她已经基本上行动如常。

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

faintness

n. 微弱，模糊，衰弱；

例句
Intermittence dizziness, is eye faintness how to return a responsibility?
间歇性头晕, 眼睛模糊是怎么回事?

had

v. 有（ have的过去式和过去分词 ），（亲属关系中）接受，拿，买到；

例句
He claimed that his parents had abandoned him...
他声称父母遗弃了他。

seized

v. 抓住( seize的过去式和过去分词 )，逮捕，捉拿，俘获；

例句
Using tanks and heavy artillery, they seized the town.
他们倚仗坦克和重型火炮占领了这个镇。

upon

prep. 在…上面，当…时候；

例句
...the doctrine of absolute monarchy based upon divine right.
以神权为基础的君主专制学说

him

pron. (he的宾格)他；

例句
They said goodbye to him as he got aboard the train at Union Station.
当他在联合火车站登上火车之际，他们向他道别。