Pronunciation: (a-blā'shun),[key] —n. 1. the removal, esp. of organs, abnormal growths, or harmful substances, from the body by mechanical means, as by surgery.
2. the reduction in volume of glacial ice, snow, or névé by the combined processes of melting, evaporation, and calving. Cf. alimentation (def. 3).
3. Aerospace.erosion of the protective outer surface (ablator) of a spacecraft or missile due to the aerodynamic heating caused by travel at hypersonic speed during reentry through the atmosphere.