Is it ensure, insure, or assure?
1707, "a becoming raw again, a breaking out afresh," from stem of Latin recrudescere "re-open" (of wounds), literally "become raw again," from re- "again" (see re-) + crudescere, from crudus "raw" (see crude (adj.)) + inchoative suffix -escere. Meaning "revival" is from 1906. Related: Recrudescency (1650s); recrudescent (1726).
recrudescence re·cru·des·cence (rē'krōō-děs'əns)
A recurrence of a pathological process or its symptoms after a period of improvement or quiesence.