ca.

from The Collaborative International Dictionary of English v.0.48

Ca \Ca\ n.
   the chemical symbol for calcium, the fifth most abundant
   element in the earth's crust, having an atomic number of 20.

   Syn: calcium.
        [WordNet 1.5]

from The Collaborative International Dictionary of English v.0.48

circa \cir"ca\ (s[~e]r"k[.a]), adv., prep. [L.]
   Approximately; about; commonly abbreviated {ca.}; -- used
   especially before dates and numerical measures; as, he was
   born circa 1650; ca. 50 feet high.

   Syn: ca.
        [PJC]

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

CA
       Certification Authority (cryptography, PKI)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

CA
       Cell Arrival (ATM)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

CA
       Channel Adapter (Infiniband)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

CA
       Computer Animation

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

CA
       Computer Associates (manufacturer)