Undercutting

EROSION of material at the foot of a CLIFF or BANK, e.g., a sea cliff, or river bank on the outside of a meander. Ultimately, the overhang collapses, and the process is repeated.
Found on http://www.ecy.wa.gov/programs/sea/swces/products/glossary.htm

undercutting

(un´der-kut″ing) the effect of scatter on a radiographic image, caused when an unattenuated x-ray beam strikes the film screen detector.
Found on http://www.encyclo.co.uk/local/21001
No exact match found