An alloy of iron and silicon that has important magnetic properties.

(inorganic chemistry) An alloy of silicon and germanium used as a semiconductor.

(inorganic chemistry) The binary compound of silicon and chlorine SiCl₄.

(inorganic chemistry) silicon dioxide (SiO₂), silica. / (inorganic chemistry) silicon monoxide (SiO).

(inorganic chemistry) The binary compound, SiGe of silicon and germanium; sometimes considered to be a simple alloy silicon germanium.

(inorganic chemistry) The binary compound of silicon and fluorine SiF₄, a colourless, poisonous gas with a pungent odour, used in the production of silicon semiconductors.

(physics) The major stable isotope of silicon, ²⁸₁₄Si, having fourteen protons and fourteen neutrons; it amounts to over 92% of the element in nature

(physics) A minor stable isotope of silicon, ²⁹₁₄Si, having fourteen protons and fifteen neutrons; it amounts to almost 5% of the element in nature

(physics) A minor stable isotope of silicon, ³⁰₁₄Si, having fourteen protons and sixteen neutrons; it amounts to 3% of the element in nature

(inorganic chemistry) A chemical compound with the formula SiO. In the atmosphere it oxidizes quickly into SiO₂, but has been detected in stellar objects and has been described as the most common oxide of silicon in the universe.