silicon
     n : 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: {Si}, {atomic
         number 14}]
Source: WordNet® 2.0

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


Source: The Jargon File