The acronym DC can mean many things, and context will tell you which one , such as:
Columbia
If you mean George C. Marshall, he died in Washington DC on October 16, 1959.
Obama's Mother in law will be staying with the family in Washington, D C.
The US Capital is Washington DC.
The Capitol Building in Washington, DC
Columbia
Illinois is West North West of Washington DC.
Washington D.C.Washington,D.C.
No - DC (District of Columbia) is not a state; it is a Federal enclave.
Washington D.C. is formally known as Washington, District of Columbia. Nowadays, it is usually referred to as simply: Washington, or the District, or simply D.C.
The address of the Diplomatic Reception Rooms is: 2201 C St NW, Washington, DC 20520
The address of the Diplomatic Rooms Foundation is: 2201 C Street NW, Washington, DC 20520