secretive
adj. （人，组织）保密的，守口如瓶的；（状态，活动）隐瞒的，秘密的；（人的表情，举止）难解的，诡秘的
例句
While the terror group established a large, secretive external operations wing bent on attacking the West, it has also cultivated a backup strategy of enabling and inspiring attacks by individuals.
虽然这个恐怖组织建立了一个庞大的、秘密的外部行动部门，致力于攻击西方，但它也形成了一种支持和鼓励个人发动袭击的后备战略。
He's very secretive about his work.
他对自己的工作讳莫如深。
《牛津词典》
Everyone is being very secretive—there's something cooking.
人人都讳莫如深—准是在搞什么鬼把戏。
