不為人知

不为人知
bùwéirénzhī
  1. not known to anyone
  2. secret
  3. unknown

CEDICT

Entry Composition

1 不 bù
  1. no; not so
  2. (bound form) not; un-
2 為人 wéirén
  1. to conduct oneself
  2. behavior; conduct; personal character
3 知 zhī
  1. to know
  2. to be aware