divergence speed[də′vər·jəns ‚spēd]
The speed of an aircraft above which no statically stable equilibrium condition exists and the deformation will increase to a point of structural failure.
The lowest IAS (indicated air speed) at which aeroelastic divergence can take place. It is the lowest speed at which the rate of change of aerodynamic deforming forces exceeds the rate of change of elastic restoring forces, or couples. It is the lowest speed at which control reversal caused by divergence can take place.