1a space formed by the removal or absence of material from the lower part of something: there may be some bigger fish in the safety of the undercut North American a notch cut in a tree trunk to guide its fall when felled.
2British the underside of a sirloin of beef. 1offer goods or services at a lower price than (a competitor):these industries have been undercut by more efficient foreign producers 2cut or wear away the part below or under (something, especially a cliff): the base of the crag is undercut permitting walkers to pass behind the falling water cut away material to leave (a carved design) in relief. 3weaken; undermine:the chairman denied his authority was being undercut
4 Tennis strike (a ball) with backspin so that it bounces high on landing.