adj.看不见的，察觉不出的，发现不了的

The virus was undetectable in his bloodstream after the treatment.
这个病毒在治疗后在他的血液中检测不到。
His stealth technology made him completely undetectable by enemy radar.
他的隐形技术使他在敌人的雷达上完全无法被探测到。
The spy's identity remained undetected for years.
那名间谍的身份多年来一直未被揭露。
The hacker's digital footprint was so clean that he managed to remain undetected for months.
黑客的网络足迹非常干净，他几个月来都未被察觉。
The new security system is designed to be undetectable to intruders.
新的安全系统设计得让入侵者无法察觉。
Her acting skills were so subtle that she could pass as a regular person without being undetectably acting.
她的演技如此细腻，以至于能以普通人的身份混迹其中而不被人察觉。
The spy satellite has an advanced camera that can capture images without being undetectable to its target.
那颗侦察卫星拥有先进的相机，能在不被目标察觉的情况下拍摄图像。
After the surgery, his scar was so well concealed that it was completely undetectable.
手术后，他的疤痕被很好地隐藏起来，完全看不出来。
The whistleblower's information was carefully encrypted, making it undetectable even by sophisticated hacking attempts.
隐匿者提供的信息被精心加密，即使是最高级别的黑客攻击也无法破解。
The magician's sleight of hand was so intricate that it left no trace, making his tricks undetectable to the audience.
魔术师的手法极其精巧，没有留下任何痕迹，观众根本无法察觉他的手法。