late 14c., "nearness in relation, kinship," later also "physical nearness" (early 15c.), from Old French propinquite (13c.) and directly from Latin propinquitatem (nominative propinquitas) "nearness, vicinity; relationship, affinity," from propinquus "near, neighboring," from prope "near" (enlarged from PIE *pro "before;" see pro-) + suffix -inquus.