apostilb: meaning, definition, pronunciation and examples
Very Rare (Specialized Technical)Technical/Scientific
Quick answer
What does “apostilb” mean?
A unit of luminance equal to one ten-thousandth of a lambert, used in the measurement of diffuse reflection or emission of light.
Audio
Pronunciation
Definition
Meaning and Definition
A unit of luminance equal to one ten-thousandth of a lambert, used in the measurement of diffuse reflection or emission of light.
A photometric unit of luminance for surfaces that are perfectly diffusing, allowing comparison of brightness between different reflective materials under specific illumination conditions.
Dialectal Variation
British vs American Usage
Differences
No significant differences exist in usage; the term is equally obscure in both varieties.
Connotations
Purely technical with no additional connotations.
Frequency
Extremely low frequency in all contexts. More likely to be encountered in older technical texts or specific standards documents than in contemporary usage.
Grammar
How to Use “apostilb” in a Sentence
[The surface] has a luminance of X apostilbs.Measure the luminance in apostilbs.Vocabulary
Collocations
Examples
Examples of “apostilb” in a Sentence
adjective
British English
- The apostilb measurement was crucial for the standard.
American English
- The apostilb value is derived from the lambert.
Usage
Meaning in Context
Business
Not used.
Academic
Used only in specialized physics or engineering papers on photometry, illumination, or radiometry.
Everyday
Never used.
Technical
Primary context. Appears in technical standards (e.g., CIE), textbooks on photometry, and illumination engineering specifications.
Vocabulary
Synonyms of “apostilb”
Strong
Neutral
Weak
Watch out
Common Mistakes When Using “apostilb”
- Confusing spelling with 'apostille'.
- Assuming it is a common or general vocabulary word.
- Incorrectly applying it to direct light sources rather than diffusely reflecting surfaces.
FAQ
Frequently Asked Questions
No, it is largely obsolete. The SI unit candela per square metre (cd/m²) or 'nit' is now standard.
One apostilb is equal to 0.0001 lamberts, or 1/π × 10^-4 candelas per square centimetre.
Primarily in historical or very specialized texts on photometry, lighting engineering, and optical physics.
The unit is also known as the 'blondel', named after the French physicist André Blondel.
A unit of luminance equal to one ten-thousandth of a lambert, used in the measurement of diffuse reflection or emission of light.
Apostilb is usually technical/scientific in register.
Apostilb: in British English it is pronounced /ˈæpəstɪlb/, and in American English it is pronounced /ˈæpəstɪlb/. Tap the audio buttons above to hear it.
Learning
Memory Aids
Mnemonic
Think: APOSTle of Light Brightness. An 'apostle' teaches; an 'apostilb' measures/teaches us about diffuse light.
Conceptual Metaphor
LIGHT AS A MEASURABLE QUANTITY.
Practice
Quiz
The apostilb is a unit of what photometric quantity?