In Spanish, caballero andante, the knight-errant: the knight who roams the world in search of adventures. Don Quixote defines him to the goatherds as a member of an instituted order, established when the times had grown worse and malice had increased, to defend maidens, protect widows, and aid orphans and the needy, and to Vivaldo as God's minister on earth and the arm through which His justice is carried out. It is the office the gentleman says he practices, and the one those around him take for madness.
Where It Appears
Quotes
that to drive a knight-errant mad with reason brings no merit or thanks: the trick lies in going mad without occasion, and letting my lady understand that if I do this when dry, what would I not do when wet?
Part One: The Penance and Micomicona, Don Quixote, to Sancho, in the Sierra Morena
it is not for knights-errant to inquire whether the afflicted, chained, and oppressed they find along the roads are going that way, or are in that distress, through their faults or their merits; it falls to them only to help them as the needy, fixing their eyes on their sufferings and not on their knaveries.
and so, considering this, I am inclined to say that in my soul I regret taking up this exercise of knight-errantry in an age as detestable as the one we now live in; because, although no danger frightens me, it does worry me to think whether gunpowder and lead will take from me the chance of making myself famous and known through the valor of my arm and the edge of my sword.
Part One: The Arms and the Captive, Don Quixote, at the inn table, in the speech on arms and letters
who was the ignoramus who signed an arrest warrant against a knight such as I am? Who did not know that knights-errant are exempt from every court of law, and that their law is their sword, their charters their courage, and their decrees their will?
Part One: The Cage and the Canon, Don Quixote, to the constables of the Holy Brotherhood, at the inn
that was the first day on which he came to know and believe, through and through, that he was a true knight-errant, and not an imaginary one, seeing himself treated just as he had read such knights were treated in past centuries.