atomic mass unit science definition

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. Also called dalton.