(physics) A unit of length, believed to be the smallest length that has physical meaning, that is defined in terms of the speed of light, the gravitational constant and the reduced Planck's constant viz:- \ell_P =\sqrt\frac{\hbar G}{c^3} \approx 1.616 252 (81) \times 10^{-35} \mbox{ meters}
noun
(physics)
A unit of length, believed to be the smallest length that has physical meaning, that is defined in terms of the speed of light, the gravitational constant and the reduced Planck's constant viz:- \ell_P =\sqrt\frac{\hbar G}{c^3} \approx 1.616 252 (81) \times 10^{-35} \mbox{ meters}