Definition
noun
(1) The measure of transmittance of an optical medium for a given wavelength. The higher the OD the lower the transmittance, the higher protection factor by a filter (e.g. goggles, viewing windows, etc.).
(2) The measure of the amount of light absorbed by a suspension of bacterial cells or a solution of an organic molecule with the use of a colourimeter or spectrophotometer.
Supplement
In microbiology, the values can be used to measure turbidity, which in turn is used to estimate the number of bacteria (or concentration of molecules like proteins) in a solution.
Abbreviation: OD
Synonym: absorbance.
See also: absorption.
Dictionary > Optical density
You will also like...
![Chemical effects on plant growth and development](https://www.biologyonline.com/wp-content/uploads/2020/02/Effect-of-Chemicals-on-Growth-Development-in-Organisms-300x168.jpg)
Effect of Chemicals on Growth & Development in Organisms
Plants and animals need elements, such as nitrogen, phosphorus, potassium, and magnesium for proper growth and developme..
![Plant Water Regulation](https://www.biologyonline.com/wp-content/uploads/2020/02/Plant-Water-Regulation-224x168.jpg)
Plant Water Regulation
Plants need to regulate water in order to stay upright and structurally stable. Find out the different evolutionary adap..
![green plant cells](https://www.biologyonline.com/wp-content/uploads/2020/02/Plant-cells-vs.-Animal-cells-252x168.jpg)
Plant Cells vs. Animal Cells
Plant cells have plastids essential in photosynthesis. They also have an additional layer called cell wall on their cell..
![vitamins](https://www.biologyonline.com/wp-content/uploads/2020/02/A-Balanced-Vitamin-Diet-–-Vitamins-A-–-K-168x168.jpg)
A Balanced Vitamin Diet – Vitamins A – K
A balanced diet is essential to a healthy organism. Insufficiency or too much of a particular element or compound, such ..
![DNA - schematic](https://www.biologyonline.com/wp-content/uploads/2020/07/DNA-300x168.jpg)
Genetic Mutations
This tutorial looks at the mutation at the gene level and the harm it may bring. Learn about single nucleotide polymorph..
![river](https://www.biologyonline.com/wp-content/uploads/2020/02/Running-Water-Freshwater-Communities-252x168.jpg)
Running Water Freshwater Communities
This tutorial introduces flowing water communities, which bring new and dithering factors into the equation for possible..