They made out a shadowy form in front of them.

他们隐约认出了前面的模糊人影。

《牛津词典》

Zebra's stripes are a form of camouflage, making the animal very difficult to see in the shadowy tall grass of the African plain.

斑马的条纹是一种隐蔽形式，使斑马在非洲平原上的高高的阴影晃动的草丛中，很难被发现。

youdao

He made headlines by warning of a shadowy "organization without form" that was using communist methods to undermine the government.

CNN: INDONESIA

When night falls on Harar, the labyrinth alleyways of the walled Old Town fall silent, and the shadowy form of a hyena slinking through the narrow streets is not an uncommon sight.

BBC: Africa��s wildlife in the raw