espionage

1. N-UNCOUNT Espionage is the activity of finding out the political, military, or industrial secrets of your enemies or rivals by using spies. 間諜活動[正式]

The authorities have arrested several people suspected of espionage. 當(dāng)局已經(jīng)逮捕了幾個涉嫌從事間諜活動的人。