Definition of carbon copy:
(n) :
a
copy produced in an alternated stack of ordinary sheets of paper and
carbon papers. The
pression applied on the top sheet (by a pen or typewriter) causes every carbon paper to release its carbon cover, thus reproducing the writing on the
subjacent layers of paper; any
duplicate
"please make a carbon copy of this contract for our records."
(v) :
to create a carbon copy of
"please carbon copy this contract for our records."