a substance, as germanium or silicon, whose conductivity is poor at low temperatures but is improved by minute additions of certain substances or by the application of heat, light, or voltage: used in transistors, rectifiers, etc.
See semiconductor in American Heritage Dictionary 4
(sĕmˌē-kən-dŭkˈtər, sĕmˌī-)
noun
Any of various solid crystalline substances, such as germanium or silicon, having electrical conductivity greater than insulators but less than good conductors, and used especially as a base material for computer chips and other electronic devices.
An integrated circuit or other electronic component containing a semiconductor as a base material.