The debye (/dɪˈbaɪ/ dib-EYE,[1] Dutch: [dəˈbɛiə]; symbol: D) is a CGS unit[2] (a non-SI metric unit) of electric dipole moment[note 1] named in honour of the physicist Peter J. W. Debye.
[note 2] Historically the debye was defined as the dipole moment resulting from two charges of opposite sign but an equal magnitude of 10−10 statcoulomb[note 3] (generally called e.s.u.
(electrostatic unit) in older scientific literature), which were separated by 1 ångström.
[note 4] This gave a convenient unit for molecular dipole moments.
The smallest SI unit of electric dipole moment is the quectocoulomb-metre,[note 9] which corresponds closely to 0.3 D.