A horse that cannot overtake another horse because it is blocked by other horses.
A horse that is racing on the rails (or fence) and is surrounded by other horses in front, outside and behind it. A horse that is boxed in is held up and unable to gain a clear passage.
When a horse is racing along the pylons and cannot improve his position in a race because of the presence of other horses in front, behind and beside him. Also called Locked in.
This has nothing to do with parking and everything to do with the ability of a horse to move into position during a race. If the announcer states that horse#3 is boxed in, it means that there are horses in front, behind and beside him thus not allowing him any room to move to another position. This is most prevelant in harness racing.
Trapped in a group of riders and unable to go forward, back or sideways. Boxed in
To be trapped in a group of riders and unable to go forward, back or sideways.
To be trapped between and behind other horses.