Found the word ‘recrudescence’ in the opening paragraph of ‘The Elf Trap’ by Francis Stevens, again from Tales Before Tolkien.

SYLLABICATION: re·cru·desce

PRONUNCIATION: rē’krōō-dĕs

INTRANSITIVE VERB: Inflected forms: re·cru·desced, re·cru·desc·ing, re·cru·desc·es

To break out anew or come into renewed activity, as after a period of quiescence.

ETYMOLOGY: Latin recrūdēscere, to grow raw again : re-, re- + crūdēscere, to get worse (from crūdus, raw).

OTHER FORMS: recru·des’cence —NOUN
recru·des’cent —ADJECTIVE