means A sudden powerful increase or forward rush — of water, electricity, crowds, emotion, or demand.

from From Latin surgere, 'to rise,' a tidy contraction of sub- ('up from below') and regere ('to lead, direct') — the same regere that gives us 'rule' and 'direct.' It reached English through Old French sourdre and the Latin verb surgere, first describing the heave and swell of the sea before it spread to anything that rises fast and hard. The root literally pictures something being led upward from underneath, which is exactly what a wave does to a calm surface.