Astounding definition: capable of overwhelming with amazement; stunningly surprising.. See examples of ASTOUNDING used in a sentence., astounding adjective amazing, striking, surprising, brilliant, impressive, astonishing, staggering, sensational (informal), bewildering, stunning, breathtaking, wondrous (archaic or literary), jaw-dropping, stupefying, gee-whizz (slang) The results are quite astounding., Definition of astounding adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more., If something is astounding, you are shocked or amazed that it could exist or happen. The results are quite astounding., Astounding is an adjective that describes something bewildering, like the astounding sight of a dog walking on two legs. When something is astounding, you might find yourself unable to speak — after all, astounding comes from the Middle English word astouned, meaning "to stun.", Synonyms for ASTOUNDING: amazing, surprising, startling, stunning, shocking, astonishing, wonderful, incredible; Antonyms of ASTOUNDING: unsurprising, normal, ordinary, typical, common, usual, customary, mundane.