semiconductor

noun

1. a substance, as silicon or germanium, with electrical conductivity intermediate between that of an insulator and a conductor: a basic component of various kinds of electronic circuit element (semiconductor device) used in communications, control, and detection technology and in computers.
2. a semiconductor device.

noun

1. a substance, such as germanium or silicon, that has an electrical conductivity that increases with temperature and is intermediate between that of a metal and an insulator, The behaviour may be exhibited by the pure substance (intrinsic semiconductor) or as a result of impurities (extrinsic semiconductor)
2. 1. a device, such as a transistor or integrated circuit, that depends on the properties of such a substance
   2. (as modifier)a semiconductor diode

n.1838, “material whose electrical conductivity is between that of a conductor and that of an insulator,” from semi- + conductor. Modern very specific sense is recorded from 1931.

1. Any of various solid substances, such as silicon or germanium, that conduct electricity more easily than insulators but less easily than conductors. In semiconductors, thermal energy is enough to cause a small number of electrons to escape from the valence bonds between the atoms (the valence band); they orbit instead in the higher-energy conduction band, in which they are relatively free. The resulting gaps in the valence band are called holes. Semiconductors are vital to the design of electronic components and circuitry, including transistors, laser diodes, and memory and computer processing circuits.

A material that conducts (see conduction) electricity, but very poorly. Silicon is the most common and familiar semiconductor. Devices made from semiconductors, such as the transistor, are the basis of the modern microelectric industry.