Definition of "whereat"

But as ſome of the Oxen in driving, miſſed their fellovvs behind and honing after them, bellovved as their nature is: Hercules chanced to heare them lovv again, and anſvver from out of the cave vvherein they had been beſtovved: vvhereat he turned back, and made haſte thither.

1659, T[itus] Livius [i.e., Livy], “[Book I]”, in Philemon Holland, transl., The Romane Historie […], London: […] W. Hunt, for George Sawbridge, […], page 6

Again she saw that bosom old, / Again she felt that bosom cold, / And drew in her breath with a hissing sound: / Whereat the Knight turn'd wildly round, / And nothing saw, but his own sweet maid / With eyes uprais'd, as one that pray'd.

1800, S[amuel] T[aylor] Coleridge, “Christabel. Part II.”, in Christabel: Kubla Khan, a Vision: The Pains of Sleep, London: […] John Murray, […], by William Bulmer and Co. […], published 1816, page 35

[…] we were driven a little to the Eaſt of the Molucca Iſlands, and about three Degrees Northward of the Line, as our Captain found by an Obſervation he took the 2d of May, at which time the Wind ceaſed, and it was a perfect Calm, whereat I was not a little rejoyced.

1726 October 28, [Jonathan Swift], “A Great Storm Described, the Long-Boat Sent to Fetch Water, the Author Goes with It to Discover the Country. […]”, in Travels into Several Remote Nations of the World. […] [Gulliver’s Travels], volume I, London: […] Benj[amin] Motte, […], part II (A Voyage to Brobdingnag), pages 150–151

Whereat in a moment of cross unruthHe thought, “All right if you want the truth!”“I don't believe it! It isn't true!It never happened! Did it, you?”Seeing no help in wings or feetShe withdrew back in self-retreat […]

2020 May 15, Robert Frost, Delphi Complete Works of Robert Frost (Illustrated) (Delphi Poets Series)‎, Delphi Classics