spike

¹spike

noun \ˈspīk\

Definition of SPIKE

: a change (as in voltage) involving a sharp increase and fall or a recording of this: as a : the pointed element in the wave tracing in an electroencephalogram b : a sharp increase in body temperature followed by a rapid fall <a fever with spikes to 103°> c (1) : the sharp increase and fall in the recorded action potential of a stimulated nerve cell that during the increasing phase corresponds to an inrush of sodium ions to the interior of the cell and during the decreasing phase corresponds to a slowing of the influx of sodium ions and to an increasing efflux of potassium ions to the exterior (2) : action potential