Blue"beard (?), n.
The hero of a mediaeval French nursery legend, who, leaving home, enjoined his young wife not to open a certain room in his castle. She entered it, and found the murdered bodies of his former wives. -- Also used adjectively of a subject which it is forbidden to investigate.
The Bluebeard chamber of his mind, into which no eye but his own must look.
Carlyle.
© Webster 1913.