say it: SEE-thing
seething is an adjective meaning "in constant agitation". It carries one recorded sense.
in constant agitation
“a seething flag-waving crowd filled the streets”
“a seething mass of maggots”
“lovers and madmen have such seething brains”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for seething come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.