mass spectrometer

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

• noun A mass spectroscope that records its data electronically.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physics, Chemistry) An analytical instrument which determines the mass of molecules of a substance or fragments of its molecules. It functions by injecting ionized moecules or molecular gragments into a vacuum chamber subjected to a strong magnetic field, in which charged particles move in a curved trajectory.

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

• noun A device used in mass spectrometry to discover the mass spectrum of a given substance.

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

• noun spectroscope for obtaining a mass spectrum by deflecting ions into a thin slit and measuring the ion current with an electrometer