Merriam-Webster's Collegiate® Dictionary, 11th Edition
SEETHE
I. verb (seethed; seething)
Etymology: Middle English sethen, from Old English sēothan; akin to Old High German siodan to seethe and probably to Old Lithuanian siausti (it) storms, rages Date: before 12th century transitive verb boil , stew , to soak or saturate in a liquid, intransitive verb boil ,
2. to be in a state of rapid agitated movement, to churn or foam as if boiling, to suffer violent internal excitement ,
II. noun
Date: 1816
a state of seething ; ebullition