[¦in·tər¦nash·ən·əl ′grav·əd·ē ‚fȯr·myə·lə] (geodesy) A formula for the acceleration of gravity at the earth's surface, stating that the acceleration of gravity is equal to 9.780327[1 + 5.3024 × 10-3 sin2φ - 5.8 × 10-6 sin22φ] m/s2, where φ is the latitude.