CMOS stands for Complementary Metal Oxide Semiconductor. A relatively new camera technology, which is evolving at a rapid rate. Previously considered an inferior technology to CCD when discussing image quality and light sensitivity, modern advancements are quickly allowing CMOS to compete head to head with CCD technology. Newer cameras are able to detect very small amounts of light comparable to CCD's, making them suitable as a direct replacement for many CCD applications.
CMOS technology is significantly more temperature and vibration tolerant when compared to CCD. CMOS imagers are also much less expensive to produce, combine this with the ability to produce sensors even smaller than 1/10 of an inch, and it won't be long before CMOS will be the dominant player in the imaging world.