disimprove

dis- +‎ improve

disimprove (third-person singular simple present disimproves, present participle disimproving, simple past and past participle disimproved)

1. (transitive, rare) to make worse
   • Jeremy Taylor

     To which may be added this advantage, that the services of churchmen are rewardable upon the church's stock: no need to disimprove the royal banks to pay thanks to bishops.

2. (intransitive, rare) to deteriorate

• improvised