noun
conspiracy
kun-SPEER-uh-see/kənˈspɪrəsi/
A secret agreement to carry out harmful or unlawful acts.
Three adults discuss their conspiracy to steal a jewel.

Etymology
Latin conspiratio meant agreement or union and came from a verb literally meaning “to breathe together.” The English sense specializes that agreement as people secretly uniting to do wrong.
In context
for example plan a joint robbery of a store they can be held liable for conspiracy even if they do not complete the robbery
More examples
- Police uncover a conspiracy to burn down the warehouse.
- She refuses to join the conspiracy against her boss.
- The prosecutor charges both men with conspiracy to commit fraud.
Forms
conspiracy · conspiracies
conspire verb — To agree secretly to commit wrongdoing.
conspirator noun — Someone who participates in a secret, harmful plot.