a natural, standing wave in the water of a lake, bay, etc., caused by changes in atmospheric pressure, seismic disturbances, winds, waves, tides, etc.: it continues after the generating force stops
Origin:
< Swiss-Fr
See seiche in American Heritage Dictionary 4
noun
A wave that oscillates in lakes, bays, or gulfs from a few minutes to a few hours as a result of seismic or atmospheric disturbances.