characterized by friendly political relations and mutual aid between countries.
Origin of good-neighbor
First recorded in 1925–30
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
also (chiefly British English) good-neighbour, adjectival phrase, in reference to U.S. foreign policy, especially in Latin America, 1928, originally in Herbert Hoover. The good neighbours is Scottish euphemism for "the fairies" (1580s).
Online Etymology Dictionary, © 2010 Douglas Harper