Ruggedized
This means the phone has some level of protection against rough use and/or rough environments.
Basic ruggedization may simply include rubber grips for improved grip and a small level of protection against drops.
Better ruggedization may provide greater durability and shock protection and/or water-resistance.
The best ruggedized phones provide certified military-grade ("milspec") protection against shock, water, and dust.
See: Mil-Spec