absorption spectrum

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The electromagnetic spectrum, broken by a specific pattern of dark lines or bands, observed when radiation traverses a particular absorbing medium and through a spectroscope. The absorption pattern of an element is unique and can be used to identify the substance of the medium.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics The characteristic pattern of dark lines or bands that occurs when electromagnetic radiation is passed through an absorbing medium into a spectroscope.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the spectrum of electromagnetic radiation that has passed through a medium that absorbed radiation of certain wavelengths