Definition of "computer" from the Oxford Dictionaries Online:
an electronic device which is capable of receiving information (data) in
a particular form and of performing a sequence of operations in
accordance with a predetermined but variable set of procedural
instructions (program) to produce a result in the form of information or
signals.
a person who makes calculations, especially with a calculating machine.
I suppose that would make ENIAC a computer, since the program is
variable, even if only by moving lots of wires.
/Jonas