con·spire / kənˈspīr/ • v. [intr.] make secret plans jointly to commit an unlawful or harmful act: they conspired against him. ∎  (of events or circumstances) seem to be working together to bring about a particular result, typically to someone's detriment: everything conspires to exacerbate the situation.

conspire XIV. — (O)F. conspirer — L. conspīrāre agree, combine, f. CON- + spīrāre breathe (see SPIRIT).
So conspiracy XIV. — AN. conspiracie, alt. of (O)F. conspiration (— L.), whence earlier ME. conspiration (XIII). conspirator XV.