If something is astounding, you are shocked or amazed that it could exist or happen. The results are quite astounding. = amazing, astonishing + astoundingly astound·ing·ly astoundingly blue eyes. so surprising that it is almost impossible to believe = astonishing
so surprisingly impressive as to stun or overwhelm; "such an enormous response was astonishing"; "an astounding achievement"; "the amount of money required was staggering"; "suffered a staggering defeat"; "the figure inside the boucle dress was stupefying"