Covert activities or situations are secret or hidden.
例句
They have been supplying covert military aid to the rebels...他們一直在暗地里向叛亂者提供軍事支援。The depth of covert racism in my own profession frightens me.我所從事的職業中暗藏著如此深的種族主義偏見，這讓我感到害怕。
N-COUNT
(小動物或獵禽可藏身的)矮樹叢，灌木叢
A covert is a group of small trees or bushes very close to each other where small animals or game birds can hide.
英漢詞典釋義
adj.
隱蔽的;不公開的;秘密的
We should learn to fight with enemy in an overt and covert way.我們應學會同敵人做公開和隱蔽的斗爭。The army carried out covert surveillance of the building for several months.軍隊對這座建筑物進行了數月的秘密監視。
英英詞典釋義
Noun
1. a flock of coots
2. a covering that serves to conceal or shelter something;
"they crouched behind the screen""under cover of darkness"
Adjective
1. secret or hidden; not openly practiced or engaged in or shown or avowed;
"covert actions by the CIA""covert funding for the rebels"