1. The number of common-midpoint traces that sample essentially the same portion of a reflector but with different offsets. For example, ‘‘12-fold’’ common-midpoint recording involves recording each subsurface point 12 times, once with each of 12 different offset distances. 2. The number of traces acquired with independent raypaths which add together to provide a single output trace, also called effort (q.v.). Recording by reciprocal raypaths usually does not count toward increased multiplicity.