British, American & Australian, American

to waste time trying to do something that will not succeed.

You're flogging a dead horse trying to persuade Simon to come to Spain with us - he hates going abroad. (usually in continuous tenses)

Do you think it's worth sending my manuscript to other publishers or I am just beating a dead horse?

• come up smelling of roses
• come up to scratch
• come up up trumps
• come up with
• come up with something
• come what may
• come within an ace of
• come within an ace of doing something
• come within an ace of something
• come within an inch of
• come within an inch of doing something
• come within a whisker of
• come within a whisker of doing something
• come within a whisker of something
• come with the territory
• comings and goings
• commit something to memory
• commit to memory
• commit to memory something
• common ground
• common-or-garden
• common touch
• compare apples and oranges
• compare notes
• conk out