A ground engaging tooth assembly for a cutting edge of a ground engaging implement may include an adapter and a ground engaging tip. The adapter may have a forward extending adapter nose having an inverted or reverse keystone-shaped contour, with the ground engaging tip having a nose cavity for receiving the adapter nose and exterior surfaces having complementary shapes to the adapter nose. The adapter nose and an adapter cavity of the tip may also be configured with complimentary surfaces that increase retention between the adapter nose and the tip when downward forces are applied to the tip. In other embodiments, the surfaces of the tip may include reliefs extending inwardly into the body of the tip to reduce weight and facilitate penetration of the tip into work material as wear material wears away from a front edge of the tip.