1. The lowest stress that is applied to a material at which extension increases without an increase in applied load.
2. The shear stress that is required to be applied to a fluid to make it begin to flow. Seeherschel–bulkley fluid.
Geology and Earth Sciences
The stress at which the yield strength of a material is exceeded and elastic behaviour gives way to viscous behaviour (seeviscosity). If continued the stress may lead to the ‘failure stress’, beyond which failure occurs.