The Collaborative International Dictionary of English v.0.48:

Silicon \Sil"i*con\, n. [See Silica.] (Chem.)
   A nonmetalic element analogous to carbon. It always occurs
   combined in nature, and is artificially obtained in the free
   state, usually as a dark brown amorphous powder, or as a dark
   crystalline substance with a meetallic luster. Its oxide is
   silica, or common quartz, and in this form, or as silicates,
   it is, next to oxygen, the most abundant element of the
   earth's crust. Silicon is characteristically the element of
   the mineral kingdom, as carbon is of the organic world.
   Symbol Si. Atomic weight 28. Called also silicium.
   [1913 Webster]

WordNet (r) 3.0 (2006):

silicon
    n 1: a tetravalent nonmetallic element; next to oxygen it is the
         most abundant element in the earth's crust; occurs in clay
         and feldspar and granite and quartz and sand; used as a
         semiconductor in transistors [syn: silicon, Si, atomic
         number 14]

The Free On-line Dictionary of Computing (19 January 2023):

silicon

   1.  The material used as the base (or
   "substrate") for most integrated circuits.

   2.  Hardware, especially integrated circuits or
   microprocessor-based computer systems (compare iron).

   Contrast: software.  See also sandbender.

   [Jargon File]

   (1996-05-28)


The Jargon File (version 4.4.7, 29 Dec 2003):

silicon
 n.

    Hardware, esp. ICs or microprocessor-based computer systems (compare iron
    ). Contrasted with software. See also sandbender.