The Collaborative International Dictionary of English v.0.48:
Cu \Cu\ n.
   the chemical symbol for copper.
   Syn: copper.
        [WordNet 1.5]
WordNet (r) 3.0 (2006):
Cu
    n 1: a ductile malleable reddish-brown corrosion-resistant
         diamagnetic metallic element; occurs in various minerals
         but is the only metal that occurs abundantly in large
         masses; used as an electrical and thermal conductor [syn:
         copper, Cu, atomic number 29]
V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):
CU
       Call Up (Unix)
V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):
CU
       see you (slang, Usenet, IRC)
The Free On-line Dictionary of Computing (30 December 2018):
CU
    "see you".
   (1997-12-01)
The Free On-line Dictionary of Computing (30 December 2018):
cu
   1.  Call Unix.
   2.  The country code for Cuba.