Antiproton production in 11.7 A·GeV/c Au+Au collisions over a wide transverse-mass coverage was studied in the AGS-E866. The inverse slope parameter increases rapidly as a function of centrality. Antiproton yields in Si+A and Au+Au collisions are consistent with the scaling with the 2/3 power of the number of participant nucleons. Transverse-mass spectra are similar to those of protons from peripheral to central Au+Au collisions.