To decimate something such as a group of people or animals means to destroy a very large number of them.
例句
The pollution could decimate the river's thriving population of kingfishers...污染可能会造成河边大量繁殖的翠鸟大批死亡。British forces in the Caribbean were being decimated by disease.加勒比海地区的英国部队有大批的人病死。
VERB
严重削弱，大幅缩减(系统或机构)
To decimate a system or organization means to reduce its size and effectiveness greatly.
例句
...a recession which decimated the nation's manufacturing industry.使该国制造业元气大伤的经济衰退
英汉词典释义
vt.
杀死或毁灭(某物)的大部
Disease decimated the population.疾病使大批人死亡。
英英词典释义
Verb
1. kill one in every ten, as of mutineers in Roman armies