retund

verb2

1. •
   (no longer used) To blunt; to make less sharp.

   • Covered with skin and hair keeps it warm, being naturally a very cold part, and also to quench and dissipate the force of any stroke that shall be dealt it, and retund the edge of any weapon. — 1691
2. •
   (figurative, no longer used) To cause to be obtuse, weak or dull.