spike
A spike is a sharp rise in the frequency for a given variable, usually immediately followed by a decrease. This sort of transient variation is often seen in the measurement of voltage or current in circuits.
In agile software development, a spike is a story that cannot be estimated until a development team runs a timeboxed investigation. The output of a spike story is an estimate for the original story.
In online gaming, a spike is a tactic whereby one or several players simultaneously inflict a massive amount of damage upon a single player or target, overwhelming the capacity of that target to regenerate or self-heal.