to beat (a person or animal) severely with a rod, whip, etc
to force or drive (oneself, one's memory, etc) into action
informal to repeat (something) so frequently as to make it uninteresting
flog the idea to death
Brit, informal to sell (something) or offer (something) for sale
I'm hoping to flog my old computer
informal to make one's way with laborious effort
flog a dead horse
to waste time or energy on worn-out or previously settled issues
flogger noun
[perhaps modification of Latin flagellare: see flagellate1]