" hole-and-corner "

1: undertaken or done so as to escape being observed or known by others;

  * e.g., " ... a hole-and-corner antiterrorist operation whose very existence has been steadfastly denied by the government "

•  Synonyms : 

•  backstairs,

•  behind-the-scenes,

•  clandestine,

•  covert,

•  furtive,

•  hugger-mugger,

•  hush-hush,

•  private,

•  privy,

•  secret,

•  sneak,

•  sneaking,

•  sneaky,

•  stealth,

•  stealthy,

•  surreptitious,

•  undercover,

•  underground,

•  underhand,

•  underhanded

•  Antonyms : 

•  open,

•  overt,

•  public