recrudesce v.

1707, of wounds, "a becoming raw again, a breaking out afresh," a noun formed in English or French on classical models from stem of Latin recrudescere "re-open" (of wounds), literally "become raw again," from re- "again" (see re-) + crudescere, verb from crudus "raw" (see crude (adj.)), + inchoative suffix -escere. Meaning "revival" is from 1906. Related: Recrudescency (1650s); recrudescent (1726).

*kreuə-, Proto-Indo-European root meaning "raw flesh."

It forms all or part of: 

creatine; creosote; crude; cruel; ecru; pancreas; raw; recrudesce; recrudescence.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit kravis- "raw flesh," krura- "raw, bloody;" Greek kreas "flesh;" Latin crudus "bloody, raw; cruel," cruor "thick blood;" Old Irish cru "gore, blood," Middle Irish cruaid "hardy, harsh, stern;" Old Church Slavonic kry "blood;" Old Prussian krawian, Lithuanian kraūjas "blood;" Old English hreaw "raw," hrot "thick fluid, serum."