0 Old HSK word(s):
人不知鬼不觉* *

Definitions from Unihan Copyright © 1991-2015 Unicode® Inc. All rights reserved.

人 man / people / mankind / someone else
不 no, not / un- / negative prefix
知 know, perceive, comprehend
鬼 ghost / spirit of dead / devil
Hsk Characters:
HSK -Characters and beyond:
GbBig5EngRadMegaTripleMultilingual