deharden

de- +‎ harden

deharden (third-person singular simple present dehardens, present participle dehardening, simple past and past participle dehardened)

1. (transitive, intransitive) To make or become less hard (resistant to pressure).
   • 2015 December 19, “Impacts of Climate Change on the Timing of the Production Season of Maple Syrup in Eastern Canada”, in PLOS ONE‎, DOI:10.1371/journal.pone.0144844:

     Below freezing winter temperatures must last long enough for the tree to begin the dehardening process necessary for the beginning of sap production; should this period become too short, tree physiology and vigor could be affected which would reduce sap production.

• adherend, hardened