conspiracy |kənˈspirəsē|
noun ( pl. –cies)
a secret plan by a group to do something unlawful or harmful : a conspiracy to destroy the government. See note at PLOT.
• the action of plotting or conspiring : they were cleared of conspiracy to pervert the course of justice.

PHRASES
a conspiracy of silence an agreement to say nothing about an issue that should be generally known.

ORIGIN late Middle English : from Anglo-Norman French conspiracie, alteration of Old French conspiration, based on Latin conspirare ‘agree, plot’ (see CONSPIRE ).