# spectrum

*Noun.*Specter, apparition. (*defdate, from early 17th c.*) .*Noun.*A range; a continuous, infinite, one-dimensional set, possibly bounded by extremes.*Noun.*Specifically, a range of colours representing light (electromagnetic radiation) of contiguous frequencies; hence electromagnetic spectrum, visible spectrum, ultraviolet spectrum, etc. (*defdate, from later 17th c.*) .*Noun.*(*chemistry*) The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).*Noun.*(*mathematics, linear algebra*) The set of eigenvalues of a matrix.*Noun.*(*mathematics, functional analysis*) Of a bounded linear operator ''A'', the set of scalar values λ such that the operator ''A—λI'', where ''I'' denotes the identity operator, does not have a bounded inverse; intended as a generalisation of the linear algebra sense.

This is an unmodified, but possibly outdated, definition from Wiktionary and used here under the Creative Commons license. Wiktionary is a great resource. If you like it too, please donate to Wikimedia.

This entry was last updated on RefTopia from its source on 3/20/2012.