Dictionary.com

molecular weight

Save This Word!

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.

QUIZZES

QUIZ YOURSELF ON “ITS” VS. “IT’S”!

Apostrophes can be tricky; prove you know the difference between it’s and its in this crafty quiz!
Question 1 of 12
On the farm, the feed for chicks is significantly different from the roosters’; ______ not even comparable.
Also called formula weight.

Origin of molecular weight

First recorded in 1875–80
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for molecular weight

molecular weight

noun

the former name for relative molecular mass
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for molecular weight

molecular weight

n.

The sum of the atomic weights of all the atoms in a molecule.formula weight
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for molecular weight

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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for molecular weight

molecular weight
[ (muh-lek-yuh-luhr) ]

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

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Get Online Help For Kids!