At this lucky moment and crisis, Don Quixote came upon his adversary, in trouble with his horse, and embarrassed with his lance, which he either could not manage, or had no time to lay in rest.
Don Quixote examined his adversary, and found that he already had his helmet on and visor lowered, so that he could not see his face; he observed, however, that he was a sturdily built man, but not very tall in stature.
Therefore, lady, let us, as I say, forestall his schemes by our activity, and let us depart at once in quest of fair fortune; for your highness is only kept from enjoying it as fully as you could desire by my delay in encountering your adversary.
…not the sword turned in its course, that single stroke would have sufficed to put an end to the bitter struggle and to all the adventures of our knight; but that good fortune which reserved him for greater things, turned aside the sword of his adversary, so that although it smote him upon the left shoulder, it did him no more harm than to strip all that side of its armour, carrying away a great part of his helmet with half of his ear, all which with fearful ruin fell to the ground,…
Don Fernando parted the officer and Don Quixote, and to their mutual contentment made them relax the grip by which they held, the one the coat collar, the other the throat of his adversary; for all this, however, the officers did not cease to demand their prisoner and call on them to help, and deliver him over bound into their power, as was required for the service of the King and of the Holy Brotherhood, on whose behalf they again demanded aid and assistance to effect the capture of…
With this, cutting short the colloquy, they mounted, and Don Quixote wheeled Rocinante round in order to take a proper distance to charge back upon his adversary, and he of the Mirrors did the same; but Don Quixote had not moved away twenty paces when he heard himself called by the other, and, each returning half-way, he of the Mirrors said to him, "Remember, sir knight, that the terms of our combat are, that the vanquished, as I said before, shall be at the victor’s disposal."
Your worship’s great courage has been fully manifested already; no brave champion, so it strikes me, is bound to do more than challenge his enemy and wait for him on the field; if his adversary does not come, on him lies the disgrace, and he who waits for him carries off the crown of victory."
There are no more uses of "adversary" in the book.
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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.