Definition of "regret"

Judge Short had gone to town, and Farrar was off for a three days' cruise up the lake. I was bitterly regretting I had not gone with him when the distant notes of a coach horn reached my ear, and I descried a four-in-hand winding its way up the inn road from the direction of Mohair.

1897 December (indicated as 1898), Winston Churchill, chapter IV, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd.

Dear humanity, we regret bein' alien bastards, we regret comin' to Earth, and we most definitely regret the Corps just blew up our raggedy-ass fleet!

2004 November 9, Halo 2 (video game cutscenes), spoken by Avery Johnson (David Scully), Microsoft Studios

He more than ever regretted his home, and with increased desire longed to see his family.

1845, The Church of England Magazine, volume 19, page 301

This [the Cage] was but one of Cluny’s hiding-places; he had caves, besides, and underground chambers in several parts of his country; and following the reports of his scouts, he moved from one to another as the soldiers drew near or moved away. By this manner of living, and thanks to the affection of his clan, he had not only stayed all this time in safety, while so many others had fled or been taken and slain: but stayed four or five years longer, and only went to France at last by the express command of his master. There he soon died; and it is strange to reflect that he may have regretted his Cage upon Ben Alder.

1886 May 1 – July 31, Robert Louis Stevenson, Kidnapped, being Memoirs of the Adventures of David Balfour in the Year 1751: […], London, Paris: Cassell & Company, published 1886

What man does not remember with regret the first time he read Robinson Crusoe?

1828, Thomas Macaulay, John Dryden

Never any prince expressed a more lively regret for the loss of a servant.

1702–1704, Edward [Hyde, 1st] Earl of Clarendon, “(please specify |book=I to XVI)”, in The History of the Rebellion and Civil Wars in England, Begun in the Year 1641. […], Oxford, Oxfordshire: Printed at the Theater, published 1707

From its peaceful bosom [the grave] spring none but fond regrets and tender recollections.

1819 June 23 – 1820 September 13, Geoffrey Crayon [pseudonym; Washington Irving], “(please specify the title)”, in The Sketch Book of Geoffrey Crayon, Gent., New York, N.Y.: […] C. S. Van Winkle, […]

Is it a vertue to have some ineffective regrets to damnation, and such a Vertue too, as shall serve to ballance all our vices?

1667, Richard Allestree, The Causes of the Decay of Christian Piety

Under squared errorloss we show that there exists unique minimax regret solution for the problem of selecting the threshold.

2002, Bernd Droge, On the Minimax Regret Estimation of a Restricted Normal Mean, and Implications

Each loss then represents this unavoidable loss plus a regret (loss due to ignorance of Ө). Subtracting these unavoidable losses, we obtain the regret table, Table 1.7, and the average regret table, Table 1.8.

2012, Herman Chernoff, Lincoln E. Moses, Elementary Decision Theory, page 12