1. n. 
Formation solids contained in a mud system, generally considered to be detrimental to the drilling operation because they produce high plastic viscosity, yield point, and gel strengths and build poor-quality filter cakes. They also occupy space that is needed for barite in high-density muds. Drill solids cause excessive wear in the mud pumps and other rig equipment. Solids control is aimed at economically and efficiently removing drill solids. This implies removal as soon as possible after they enter the mud system, while the particles are at their largest size.
Alternate Form: drilled solids