Now I see you contending against the woman like an adversary.
Unfortunately, if a messenger suspected the letter might contain valuable information, he could make far more money selling the information to adversaries than he could delivering the letter properly.
There are no more uses of "adversary" in the book.
Show samples from other sources
Then, again, our military training is in many respects superior to that of our adversaries.
Thucydides -- Pericles’s Funeral Oration
Finally, it was rumored, there would be complete information-sharing among all of these previously disconnected and even adversarial entities, and when they were coordinated, and once all the health data they’d collected was shared, most of this made possible through the Circle and more important, TruYou, viruses could be stopped at their sources, diseases would be tracked to their roots.