Quiz: Remember the definition of mal de mer?
"soaked or softened in water," 1820, earlier "resembling something that has been boiled a long time" (1590s), originally "boiled" (c.1300), from Old English soden "boiled," strong past participle of seoþan "to cook, boil" (see seethe). For sense evolution from "heat in water" to "immerse in water" cf. bath.
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 (cf. 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, e.g. "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.
to boil (Ex. 16:23).