Back the wrong horse: The act of supporting someone (or an organization, company, something, etc) that cannot possibly succeed. Basically, you’ve made the wrong bet and you’re going to lost everything you’ve invested.
Caligula’s horse: An impostor.
Charley horse: A specific type of muscle spasm that is very painful and usually only happens in the legs.
Don’t change horses at midstream: Keep up with it. You shouldn’t try to switch directions in the middle of something because you are now committed and changing directions is impossible anyway.
Don’t put the cart before the horse: Don’t do things in the incorrect order or you will regret it. There is a natural order to things, so make sure to do A first, followed by B, C, etc.
Flog a dead horse: Talking about something and going on and on even though no one else in the room is really interested in what you’re saying, usually because the topic has already been discussed so many times that everyone is sick of it.
From the horse’s mouth: From someone who is in a position of power and authority. If this person is stating the facts, then they are truly the facts and he or she should be listened to.
Get off your high horse: Stop being so arrogant and learn a little humility. This sentence is used when you want to make a point to someone that they are being overconfident and that they should slow down and smell the roses.
Hold you horses: Hold on, you’re going too fast. An expression used to indicate that things are moving at a very fast pace and that slowing down is the right course of action.
Horse opera: A western movie that follows a specific formula.
Horse pucky: Foolish words are being uttered by someone and you should not listen to them. Mostly heard in America. Example: she’s full of horse pucky; don’t listen to her!
Horse sense: Common sense.
Horse trading: Intelligent, high-class negotation.
Horse’s ass: A foolish and clumsy person.
I could eat a horse: A phrase that you utter when you are starving and want some food right now.
If two ride on a horse, one must ride behind: A proverb that indicates that when two people join together to do something, one of them will tend to be the leader at times and the other will be more of a follower at other times. Embracing this dynamic is key.
If wishes were horses, then beggars would ride: Wishing is a futile effort that accomplished nothing in the real world. If you want to get something done or achieve something, put in the hard work.
Trojan horse: A computer virus that sends sensitive, personal information to someone else.
You can lead a horse to water, but you can’t make it drink: You can give someone all the opportunities they could ever wish for, but unless they take action on them and make something happen, it’s all for naught.