1. n. [Geophysics]

Seismic events whose energy has been reflected once. Multiples, in contrast, are events whose energy has been reflected more than once. A goal of seismic data processing is to enhance primary reflections, which are then interpreted as subsurface interfaces.

See: event,  long-path multiple,  multiple reflection,  peg-leg multiple,  reflection,  short-path multiple,  vertical seismic profile