pí​máo

superficial knowledge

皮毛 pí​máo
superficial knowledge noun
a smattering or superficial knowledge of a subject; the surface level of a matter

He has only a superficial knowledge of Japanese.

fur
fur; animal pelt; fur clothing
skin and hair
the outermost parts of the human body, such as the skin and hair

Frequency

Movie subtitles
1.79 per million appears in 1% of films
Written text
2.61 per million

Sources