Both Uses of

conspiracy
in
Utopia, by Thomas More

The only danger to be feared from them is their conspiring against the government; but those of one division and neighbourhood can do nothing to any purpose unless a general conspiracy were laid amongst all the slaves of the several jurisdictions, which cannot be done, since they cannot meet or talk together; nor will any venture on a design where the concealment would be so dangerous and the discovery so profitable.†
*

conspiracy = a secret agreement or plot

Therefore I must say that, as I hope for mercy, I can have no other notion of all the other governments that I see or know, than that they are a conspiracy of the rich, who, on pretence of managing the public, only pursue their private ends, and devise all the ways and arts they can find out;†

Definition:

a secret agreement or plot -- especially to do something illegal or harmful