Definition of STAGNANT in the Definitions.net dictionary. Meaning of STAGNANT . What does STAGNANT mean ? Information and translations of STAGNANT in the most comprehensive dictionary definitions resource on the web. stagnant meaning , definition , what is stagnant : stagnant water or air does not move or f...: Learn more. Stagnant means not flowing or moving, and smelling unpleasant, or not growing or developing. Learn more about the word, its synonyms, and its usage in different contexts with Cambridge Dictionary. stagnant (comparative more stagnant , superlative most stagnant ) Lacking freshness, motion, or flow; decaying through stillness. synonym Synonym: standing a stagnant pool stagnant water (figurative) Without progress or change; stale; inactive. a stagnant economy stagnant prices