A global accurate double-many-body expansion potential-energy surface is reported for the electronic ground state of N2O. The new form is shown to accurately mimic the ab-initio points calculated at the multireference configuration interaction level using the aug-cc-pVTZ basis set and the full-valence-complete-active-space wave function as reference. To improve the calculated raw energies, they have been extrapolated to the completed basis set limit and most importantly to the full configuration-interaction limit by correcting semiempirically the calculated dynamical correlation with the double-many-body expansion-scaled external correlation method. The topographical features of the novel potential-energy surface were examined in detail and compared with those of other potential functions available in the literature. Good agreement with the experimental data is observed.