atomic mass unit

noun

: a unit of mass for expressing masses of atoms, molecules, or nuclear particles equal to ¹/₁₂ the mass of a single atom of the most abundant carbon isotope ¹²C

called also dalton

Example Sentences

Recent Examples on the Web

What’s more, the large compounds are likely fragments of even larger parent molecules that could weigh thousands of atomic mass units, Postberg says. —National Geographic, 27 June 2018

Previously, Cassini detected lighter, gassy molecules such as methane and ethane, which contain one or two carbon atoms and a smattering of hydrogens; these molecules weigh in at around 15 atomic mass units. —National Geographic, 27 June 2018

Word History

First Known Use

circa 1942, in the meaning defined above

Kids Definition

atomic mass unit

noun

: a unit of mass for expressing masses of atoms, molecules, or nuclear particles that is equal to frac::1/12 of the atomic mass of the most abundant kind of carbon

Medical Definition

atomic mass unit

noun

: a unit of mass for expressing masses of atoms, molecules, or nuclear particles equal to ¹/₁₂ the mass of a single atom of the most abundant carbon isotope ¹²C

called also dalton