Also found in: Acronyms, Encyclopedia.
A unit of brightness equal to 0.1 millilambert.
[G. apo, from + stilbē, lamp]
apostilbAn obsolete, non-SI (International System) unit of light, defined as the amount of light emitted from a diffusing surface corresponding to 1.0 lumen/m2.
The luminance of a perfectly diffusing surface that reflects 1 lumen per square metre. This measure is often used in visual field analysis, where the luminance of the background and targets is measured in apostilb.