molecular weight

noun Chemistry.
the average weight of a molecule of an element or compound measured in units once based on the weight of one hydrogen atom taken as the standard or on 1/16 (0.0625) the weight of an oxygen atom, but after 1961 based on 1/12 (0.083) the weight of the carbon-12 atom; the sum of the atomic weights of all the atoms in a molecule. Abbreviation: mol. wt.
Also called formula weight.


Origin:
1875–80

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World English Dictionary
molecular weight
 
n
the former name for relative molecular mass

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

molecular weight n.
Abbr. mol wt, MW
The sum of the atomic weights of all the atoms in a molecule. Also called formula weight.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
molecular weight  
The sum of the atomic weights of the atoms contained in a molecule. Also called relative molecular mass.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary
molecular weight [(muh-lek-yuh-luhr)]

The sum of the atomic weights of all the atoms in a molecule.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Example sentences
The first instrument separates all the components of the mixture and the other measures the molecular weight of each.
We also wanted to understand how the molecular weight changed as a function of our salt concentration.
Natural gas forms when the temperature is higher, favoring lighter molecular weight alkanes.
One compound is of low molecular weight and another of high molecular weight.
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