IPA: //ˌriːkruːˈdɛsəns//
KK: /riːˈkruːdəsəns/
The sudden return of a disease or its symptoms after a time when it seemed to improve or go away.
After several months of feeling better, she experienced a recrudescence of her illness.
Recrudescence is formed from "re-" (meaning again) and "crudescere" (from Latin, meaning to grow raw or fresh). The word describes the process of a disease or condition returning or reappearing after a period of remission, essentially meaning to grow fresh again.
Think of something returning or 'growing again' — 're-' means again, and 'crudescere' means to grow fresh.