It is possible it is from the Portuguese for "cord."
I happened to find yet another obscure (to all but the horseworld) term and it's meaning:: "Corredo" or in English "Corridor." This is also Portuguese and refers to the small room used for working and training the horse. It may be open to the sky, as I recall, but high-walled, often too, part of another building.
You can see in one of the early videos from a film of Nuno Oliveira working a horse in just such a room.
I've considered it a very interesting approach to minimizing rein cues and following the Iberian origin of our "fencing," the horse - that is, using a high fence or barn wall or other impassible barrier to work the horse against so that a light cue is followed by a physical barrier for the horse to react to.
In stock horse or western reining, this would be used mostly in training for the roll-back, a 180 degree change of direction executed by turning over the hindquarters and departing, and for the more spectacular sliding stop.
Though it's been criticized it is obviously far superior to using the rein and bit and pulling the horse's mouth. The fence or wall replaces any rein pressure. It would, of course, be excellent strategy for beginning work bitless, or bridleless. Or with cordeo.
Love is Trust, trust is All
So say Don, Altea, and Bonnie the Wonder Filly.