Late Middle English (in an earlier sense). From re- + boil, probably partly after Anglo-Norman and Middle French rebouillir to boil again, to spoil (wine) by refermenting. Compare classical Latin rebullīre to bubble up, to cause to bubble up, Old Occitan rebulhir to retemper (steel), Spanish rebullir to boil again, Italian ribollire to boil, to ferment, to boil again.