Exercise and training that takes place during the off-season for ski racers.
Called "dryland" becasuse... well, you aren't on the wet snow. I'm sure this term is employed in other sports as well, but I'm most familiar with these terms.
Exercises often include aerobic,anaerobic, strength, and agility training, most often focusing on the lower body, most specifically the legs.
Dryland training during the offseason is prety much essential to ensure a successful racing season.