See other posts about boundaries and boundary lines.
Terrain autorisé is territory where a boule or jack may move safely. In contrast, terrain interdit is territory that kills balls that enter it. A live boule or jack immediately becomes dead if it lands in, or crosses, a patch of terrain interdit.
For the sake of consistency, we prefer to translate terrain autorisé and terrain interdit as “in-bounds” and “out-of-bounds”. However, the expression terrain interdit literally means “forbidden territory” and other translators prefer to translate it as “dead ground”.
A patch of dead ground can come between the jack and the throwing circle if the terrain has an irregular shape, so that a patch of terrain interdit intrudes into the terrain autorisé. You can see a good example in the petanque court in Urban Park, Los Alamos, New Mexico, USA.
The court is designed to fit around several pre-existing trees. On this terrain it is possible for a shot jack to fly sideways and end up around a corner, so that there is dead ground (an out-of-bounds area, terrain interdit) between it and the throwing circle.
Some umpires interpret the rules so that there is a second kind of situation in which a patch of dead ground can come between the jack and the throwing circle. We discuss that situation in our post on the Puddle Rule.