Sentence:  In preparing the contract, we'll make a <WSD>carbon copy</WSD> for our records. 
Meaning of the word marked with <WSD> tags:  A copy produced in an alternated stack of ordinary sheets of paper and carbon papers. The pressure 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.