secret service noun
Learner's definition of SECRET SERVICE
1
the Secret Service : a U.S. government department in charge of protecting elected leaders of the U.S. and visiting leaders（保护美国民选领导人和来访国家领导人的）美国特工处
2
[singular] : a government department that protects a country's secrets and obtains secret information about other countries（保卫本国秘密并且获取他国情报的）情报部门