sweal
Sweal (verb) means to burn gently and gradually.
Etymology
Came into English via Middle English swelen, from Old English swelan ("to burn, be burnt up, inflame") (compare Old English swǣlan ("to burn")), from Proto-West Germanic *swelan, from Proto-Germanic *swelaną ("to smoulder, burn slowly, create a burningly cold sensation"), from Proto-Indo-European *swel- ("to shine, warm, smoulder, burn"). It is cognate with Dutch zwelen ("to smoulder"), Low German swelen ("to smoulder"), German schwelen ("to smoulder"), and Icelandic svala ("to cool"), and is related to swelter.