ABSORBANCE

n. percentage of the passage of light through a liquid; degree to which something is absorbed

In spectroscopy, the absorbance A is defined as, where is the intensity of light at a specified wavelength λ that has passed through a sample (transmitted light intensity) and is the intensity of the light before it enters the sample or incident light intensity. Absorbance measurements are often carried out in analytical chemistry, since the absorbance of a sample is proportional to the thickness of the sample and the concentration of the absorbing species in the sample, in contrast to the transmittance  of a sample, which varies exponentially with thickness and concentration. See the Beer-Lambert law for a more complete discussion.
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Absorbance /ab·sor·bance/ 1. in analytical chemistry, a measure of the light that a solution does not transmit compared to a pure solution. Symbol. [more]Absorbance - Community and Resources

n. absorbance, percentage of the passage of light through a liquid; degree to which something is absorbed

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(A, D, E) A measure of the amount of light absorbed by a sample. The absorbance (A) equals minus the base-10 log of the transmittance .