Sensitive Compartmented Information (SCI) Oxford  Dictionary of the US Military:

Information and materials bearing special community controls indicating  restricted handling within present and future community intelligence collection  programs and their end products for which community systems of compartmentation  have been or will be formally established; in short, a designated category of  intelligence materials which by virtue of their means of collection or other  extraordinary aspect of their nature required special handling and more than  routine protection.

Ever wonder what kind of agreement you have to sign to gain access to America’s top secrets?  You can  read the full form you must sign before you are authorized access to Sensitive Compartmented Information (SCI). Below is a snap shot of paragraphs 3 and 4 that makes it very clear why the Pentagon and Panetta are not happy.

Sensitive Compartmented Information SCI

SCI is also called codeword information.  Compartmentation adds a level of need to know in addition to clearance level.  Only those with a special designation, obtained via a single scope background investigation (SSBI), may have access SCI.