|ən+ noun
1. archaic : lack of conformity
2.
a. : lack of continuity in deposition between rock strata in contact corresponding to a period of nondeposition, weathering, or erosion either subaerial or subaqueous prior to the deposition of the younger beds and consequently to a gap in the stratigraphic record
b. : the surface of contact between unconformable strata — compare disconformity , nonconformity