invisibly
adv. 看不见地；看不出地
例句
He looked at me and nodded, almost invisibly.
他看着我点了点头，几乎让人看不出来。
《牛津词典》
A thin coil of smoke rose almost invisibly into the sharp, bright sky.
一缕轻烟几乎不见踪迹地升上了耀眼的晴空。
《柯林斯英汉双解大词典》
Space travel can be so delightful but at the same time invisibly dangerous.
太空旅行是如此令人愉快，但同时又存在无形的危险。
