| spectrum | |
| 1. n. A range; a continuous, infinite, one-dimensional set, possibly bounded by extremes. | |
| 2. n. Specifically, a range of colours representing light (electromagnetic radiation) of contiguous frequencies; hence electromagnetic spectrum, visible spectrum, ultraviolet spectrum, etc. | |
| 3. n. (psychology, education) The autism spectrum. | |
| 4. n. (chemistry) The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.). | |
| 5. n. (mathematics, linear algebra) The set of eigenvalues of a matrix. | |
| 6. n. (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; inten | |
| 7. n. (abstract algebra, algebraic geometry) The set, denoted Spec(R), of all prime ideals of a given ring R, commonly augmented with a Zariski topology and considered as a topological space. | |
| 8. n. (obsolete) Specter, apparition. | |
| 9. n. The image of something seen that persists after the eyes are closed. | |
