Definition of "astounding"

[Y]ou ſhall heare the Scythian Tamburlaine: / Threatning the world with high aſtounding tearms / And ſcourging kingdomes with his conquering ſword.

c. 1587–1588, [Christopher Marlowe], “The Prologue”, in Tamburlaine the Great. […] The First Part […], 2nd edition, part 1, London: […] [R. Robinson for] Richard Iones, […], published 1592; reprinted as Tamburlaine the Great (A Scolar Press Facsimile), Menston, Yorkshire, London: Scolar Press, 1973,

Wasted in darkness down the pitchy wave, / We saw the Stygian pool her borders lave, / Fed by th’ astounding cataract on high.

1802, Dante Alighieri, “Canto VII”, in Henry Boyd, transl., The Divina Commedia of Dante Alighieri: Consisting of the Inferno—Purgatorio—and Paradiso. Translated into English Verse, […] In Three Volumes, volume I (Inferno), London: Printed by A[ndrew] Strahan, […]; for T[homas] Cadell, Jun. and W[illiam] Davies, […], stanza XVIII, page 152

Signor Jupe […] was also to exhibit "his astounding feat of throwing seventy-five hundred-weight in rapid succession backhanded over his head, thus forming a fountain of solid iron in mid-air, a feat never before attempted in this or any other country […]."

1854, Charles Dickens, “A Loophole”, in Hard Times. For These Times, London: Bradbury & Evans, […], book the first (Sowing), page 14

This is going to be the most astounding thing you’ve ever heard of, sir, and I say that knowing that a man of your caliber in your profession must have known some astounding things in his time.

1930, Dashiell Hammet, “The Emperor’s Gift”, in The Maltese Falcon, New York, N.Y., London: Alfred A[braham] Knopf, page 148