conspirator
noun /kənˈspɪrətə(r)/
  /kənˈspɪrətər/
 - a person who is involved in a conspiracy (= a secret plan to do something illegal)
- political conspirators
 - The emperor pardoned five of the conspirators.
 
Word Originlate Middle English: from Old French conspirateur, from Latin conspirator, from conspirat- ‘agreed, plotted’, from the verb conspirare, from con- ‘together with’ + spirare ‘breathe’.