Wiktionary
alt. 1 (context dated nautical English) To attempt to get extra work out of a ship's crew during the dead horse period. 2 (context British idiomatic English) To attempt to get more out of something that cannot give more; to attempt to arouse fresh interest in something that is either hopeless or already settled. vb. 1 (context dated nautical English) To attempt to get extra work out of a ship's crew during the dead horse period. 2 (context British idiomatic English) To attempt to get more out of something that cannot give more; to attempt to arouse fresh interest in something that is either hopeless or already settled.
Usage examples of "flog a dead horse".
My husband is to town to flog a dead horse with the Elder Brethren concerning his difficulties and Marvell has gone to challenge Gilby for the rights to claim Sunk Island which all men say should be no man's but Crown land, being risen from the river by the grace of the Lord, I do not think one may draw a line between Marvell and Gilby in this matter both being out for themselves and anxious to secure the island for no other benefit but their own.
If you're going to flog a dead horse, why don't you at least let the poor bugger rest in peace until Monday?