Noah Webster's New International Dictionary of the English Language

1. (v. i.) To plot secretly; as, to conspire to commit murder; to make an agreement, esp. a secret agreement, to do some act, as to commit treason or a crime, or to do some unlawful deed; to plot together.

2. (v. i.) To concur to one end; to agree.

3. (v. t.) To plot; to plan; to combine for.