The mass that a particle with a wavelength equal to the Planck length would have, equal to (ℏc/G)½ (where c is the speed of light), i.e. 2.177 × 10−5 gram.
Origin
1960s.
Definition of Planck mass in US English:
Planck mass
noun
Physics
The mass that a particle with a wavelength equal to the Planck length would have, equal to (ℏc/G)½ (where c is the speed of light), i.e. 2.177 × 10−5 gram.