be flogging a dead horse(redirected from be beating a dead horse)
be flogging a dead horseBRITISH or
be beating a dead horseAMERICAN
If someone is flogging a dead horse, they are wasting their time trying to achieve something that cannot be done. After putting in all that hard work it feels like we're flogging a dead horse — it's all very discouraging. You're beating a dead horse on this. These guys are defeated.