A more thorough explanation:

Definition: An opponent; especially, opposing counsel.

Examples:

• During the trial, the defense attorney and the prosecutor were adversaries.
• The two teams were adversaries on the field, but friends off the field.

The term "adversary" refers to someone who is opposing or competing against another person or group. In the legal context, an adversary is often the opposing counsel in a court case. The examples illustrate this definition by showing how the defense attorney and prosecutor are adversaries in a trial, and how two sports teams can be adversaries on the field.