Chasma is the term planetary geologists use for a deep, steep-sided canyon. 88 named features carry it, across 2 of the 14 mapped worlds, the largest being Parga Chasmata on Venus at 11,000 km.
Ranked across every mapped world, by catalogued diameter.
Naming themes are set per world, so one descriptor can draw on very different sources depending on where it sits. Across all 88 chasmata, 38 categories appear.