The Free On-line Dictionary of Computing (18 March 2015):
(PC) A register in the central processing unit
that contains the addresss of the next instruction to be
executed. After each instruction is fetched, the PC is
automatically incremented to point to the following
instruction. It is not normally manipulated like an ordinary
register but instead, special instructions are provided to
alter the flow of control by writing a new value to the PC,
e.g. JUMP, CALL, RTS.
IBM call it the Instruction Address Register.