(1) The process of applying, to a measured or calculate value of gravity, the sum δ _c of the following gravity corrections in the order listed: (a) the condensation gravity correction δg _c; (b) the free air gravity correction δg _f; and (c) the cylindrical Bouguer gravity correction δg _Bc. The advantage of the condensation gravity reduction over, e.g., the Bouguer gravity reduction, is that the former changes the location of the geoid (or other reference surface) by less than 3 meters, whereas the Bouguer gravity reduction may change that surface's location by hundreds of meters. (2) The same as the previous definition but with a topographic gravity correction added and with the condensation gravity correction modified to allow for the effect of topography. (3) The quantity δ _c defined in the first definition. (4) The sum of the gravity corrections applied according to the second definition. The condensation gravity reduction is also called Faye's gravity reduction and the Helmert gravity reduction.