Pain borne over time. Suffering is not the same as pain — it is what pain becomes when it has nowhere to go.
Latin sufferre (to bear up under, to endure), from sub (under) + ferre (to carry, to bear); pain carried over time and pain with nowhere to go were, from the start, the same word for bearing a weight.
Pain borne over time, which is not the same thing as pain itself. What pain becomes when carrying it has nowhere left to be put down.