1.NounA lack of continuity, regularity or sequence; a break or gap. .mw-parser-output .defdate{font-size:smaller}
"structural discontinuity; sharp discontinuity; detect a discontinuity; The data shows a clear discontinuity in temperature around 1990.; Geologists noted a discontinuity between the two rock layers."
2.NounA point in the range of a function at which it is undefined or discontinuous.
3.Nouna subterranean interface at which seismic velocities change