Definitions for "Fatigue Limit"
The maximum stress below which a material can presumably endure an infinite number of stress cycles. If the stress is not completely reversed, the value of the mean stress, the minimum stress, or the stress ratio should be stated.
The maximum value of the applied alternating stress that the material can withstand without failure ever occurring.
A characteristic of the material and its geometry. If a material is loaded below the fatigue limit, the material will not fail, regardless of the number of cycles it is subject to.