A Critical Care Unit is a specialised unit within a hospital. It provides continuous monitoring and treatment for people who need acute care. Found on http://www.encyclo.co.uk/visitor-contributions.php
A CCU (Communications Concentrator Unit) is a small computer connected between a main computer and one or more serial devices operating as an intermediary to relieve the main computer of much of the routine work connected with receiving information from the serial devices. Found on http://www.probertencyclopaedia.com/browse/GC.HTM
Correctional Custody Unit, a hard-labor and heavy discipline unit overseen by MPs or Navy Masters-at-Arms to which Marines and Sailors found guilty of minor UCMJ offenses through NJP are sent for up to 30 days in lieu of confinement in the brig. Found on http://www.translationdirectory.com/glossaries/glossary119.htm