Something that is perceptible can barely be seen or noticed.
indiscernible , imperceptible
Pasternak gave him a barely perceptible smile.
帕斯特纳克对他报以一个几乎察觉不到的微笑。
a perceptible shift in US policy.
美国政策上一个明显的调整。
There was no perceptible difference in temperature.
在温度上没有明显的区别。