undetected

adj

• ① 未被发现[发觉、识破]的
  • It's very important to her safety that she (should) remain undetected.她保持不被人发现,对她的安全是非常重要的(★【口】通常不用should)。
  • He tried to enter the building undetected.他试图不被人发现而进入那栋建筑物。