mollifier

mollify +‎ -er

mollifier (plural mollifiers)

1. One who mollifies.
   • Lord Halifax

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

2. (mathematics) 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.
   • 2009, Notices of the American Mathematical Society‎, volume 56, number 6:

     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.