mollifier

noun

1. One who mollifies.

   “[…] the Lord Treasurer, who ever secretly feigned himself to be a Moderator and Mollifier of the Catholicks Afflictions […]”

2. An "approximation to the identity", a smooth function with special properties, used in distribution theory to create sequences of smooth functions approximating nonsmooth (generalized) functions, via convolution.

   “I particularly remember how, at that time, I was using his mollifier method to study the zero density of L-functions and was stuck with something.”