unsolve

From un- +‎ solve.

unsolve (third-person singular simple present unsolves, present participle unsolving, simple past and past participle unsolved)

1. (obsolete) To solve. [17th c.]
   • 1631, Francis Quarles, The History of Samson:

     Perchance, my Fancy would have bin so kinde, / T‘ unsolve the doubts of my perplexed minde.

2. To undo or remove the solution to a problem; to put something into an unsolved state.
   • 2001, Dave Rosi, One Good Deed:

     “But I cannot allow you to use my cousin to solve or, I suppose, more precisely, to unsolve your case.”

   • 2011, Solomon Belay Faris, (title):

     Ethiopia and the Generation That Unsolves Problems.

• unloves, vulnose