seethe: [OE] Seethe was once the standard word for ‘boil’, until it began to be overtaken by the French import boil in the Middle English period. In the 16th century a new meaning, ‘soak’, emerged, now preserved only in the past participle sodden. And the modern metaphorical ‘be violently agitated’ came on the scene in the 17th century. The word goes back to a prehistoric Germanic *seuth-, which also produced German sieden and Dutch zieden ‘boil’. English suds probably comes from a variant of the same base. => sodden
seethe (v.)
Old English seoþan "to boil," also figuratively, "be troubled in mind, brood" (class II strong verb; past tense seaþ, past participle soden), from Proto-Germanic *seuthan (cognates: Old Norse sjoða, Old Frisian siatha, Dutch zieden, Old High German siodan, German sieden "to seethe"), from PIE root *seut- "to seethe, boil."
Driven out of its literal meaning by boil (v.); it survives largely in metaphoric extensions. Figurative use, of persons or populations, "to be in a state of inward agitation" is recorded from 1580s (implied in seething). It had wider figurative uses in Old English, such as "to try by fire, to afflict with cares." Now conjugated as a weak verb, and past participle sodden (q.v.) is no longer felt as connected.
