carbon copy

Short definition from Wiktionary

Noun

1. 1
   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.
2. 2
   Any duplicate.
3. 3
   A duplicate copy of an email.
4. 4
   Alternative form of carbon copy.

Verb

1. 1
   To create a carbon copy of.
2. 2
   To send a duplicate copy of an email to.
3. 3
   Alternative form of carbon copy.