From The Art and Popular Culture Encyclopedia
Rocinante is Don Quixote's horse in the novel Don Quixote by Miguel de Cervantes. In many ways, Rocinante is not only Don Quixote's horse, but also his double: like Don Quixote, he is awkward, past his prime, and engaged in a task beyond his capacities.
Rocín in Spanish means a work horse or low-quality horse, but can also mean an illiterate or rough man. There are similar words in French (roussin; rosse), Portuguese (rocim), and Italian (ronzino). The etymology is uncertain.
The name is a complex pun. In Spanish, ante has several meanings and can function as a standalone word as well as a suffix. One meaning is "before" or "previously". Another is "in front of". As a suffix, -ante in Spanish is adverbial; rocinante refers to functioning as, or being, a rocín. "Rocinante," then, follows Cervantes' pattern using ambiguous, multivalent words, common throughout the novel.
Rocinante's name, then, signifies his change in status from the "old nag" of before to the "foremost" steed. As Cervantes describes Don Quijote's choice of name: nombre a su parecer alto, sonoro y significativo de lo que había sido cuando fue rocín, antes de lo que ahora era, que era antes y primero de todos los rocines del mundo. - "a name, to his thinking, lofty, sonorous, and significant of his condition as a hack before he became what he now was, the first and foremost of all the hacks in the world."
In chapter 1, Cervantes describes Don Quixote's careful naming of his steed: "Four days were spent in thinking what name to give him, because (as he said to himself) it was not right that a horse belonging to a knight so famous, and one with such merits of his own, should be without some distinctive name, and he strove to adapt it so as to indicate what he had been before belonging to a knight-errant, and what he then was."