atomic mass unit

American  

noun

Physics.

1. Also called dalton.  a unit of mass, equal to 1/12 (0.0833) the mass of the carbon-12 atom and used to express the mass of atomic and subatomic particles.

2. (formerly) a unit of mass, equal to 1/16 (0.0625) the mass of an oxygen atom having atomic mass 16. amu, AMU

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atomic mass unit British  

noun

1.  amu.  Also called: unified atomic mass unit.   dalton.  a unit of mass used to express atomic and molecular weights that is equal to one twelfth of the mass of an atom of carbon-12. It is equivalent to 1.66 × 10 ^–27 kg

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atomic mass unit Scientific  

1. A unit of mass equal to 1/12 the mass of an atom of the most common isotope of carbon (carbon 12), which is assigned a mass of 12 and has a value of 1.660 × 10 ^{- 24} grams. A hydrogen atom has a mass of 1 atomic mass unit since its mass is 1/12 the mass of carbon 12.

2. Also called dalton

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Etymology

Origin of atomic mass unit

First recorded in 1950–55

Example Sentences

The deuteron mass, md, is then found in atomic mass units, where one atomic mass unit is defined as one-twelfth the mass of the carbon atom.

From Nature

Extrapolating these rates over geologically important periods of time and merging with modeled radiolysis data yields a predicted 1000-fold decrease in 100–atomic mass unit organic molecules in ∼650 million years.

From Science Magazine

Even a short jog can help you shed a few septillion daltons, a unit of mass often used in biochemistry that is equivalent to the atomic mass unit.

From Scientific American