English word spectrum comes from Proto-Indo-European *speḱ-, Proto-Indo-European - -yeti, and later Proto-Indo-European *spéḱyeti (To be looking at, to keep looking at.)
| Dictionary entry | Language | Definition |
|---|---|---|
| *speḱ- | Proto-Indo-European (ine) | to look |
| - -yeti | Proto-Indo-European (ine) | |
| *spéḱyeti | Proto-Indo-European (ine) | To be looking at, to keep looking at. |
| *spekjō | Proto-Italic (itc-pro) | To observe, to see. |
| specio | Latin (lat) | I observe, watch, look at. |
| spectrum | Latin (lat) | Apparition, specter. Appearance, image. |
| spectrum | English (en) | (chemistry) The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).. (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 [...] |