There is a number of interesting expressions in the English language using the word horse. Here are some of the more common ones.
Workhorse – originally it referred to a horse that was used for work as opposed to horses used for pleasure. Eventually it came to mean a person who works hard or does most of the work in a group.
Showhorse – as its name suggests, this is a horse that is prized for its appearance and not for any work it can perform. It is also used to describe a person who is a “showoff” – a person who acts pretentiously or purposely displays his possessions or achievements to gain attention.
Dark horse – this originally referred to a racehorse of which little was known but which excelled in a competitive race to win it. It has since been used to describe a person of which little is known who runs for a public office and gains attention for rising to the top among his competitors. -
To horse around – this means to play or indulge in frivolous activity. Children can become rambunctious when playing and as a warning to calm down a parent might command, “Stop horsing around!”
Don’t look a gift horse in the mouth – this means “don’t question the value of a gift”. The expression comes from how people would determine the age and physical condition by looking at its teeth. The older the horse, the more its teeth appeared to be long. This is where the expression long in the tooth comes which means “to be old”.
Straight from the horse’s mouth – refers to information that comes directly from the person providing it. If you are asked where you got some information about a person, you can say, “I got it straight from the horse’s mouth,” to indicate that the individual in question directly told you.
A horse of a different color – refers to something that is very different from what is being discussed.
Horse sense – this has the same meaning as “common sense”. It is said to come from a novel written in 1832 called “Westward Ho!”. Cowboys were considered to have good common sense.
Horse’s ass – this expression is used to describe a person acts or speaks foolishly that usually results I others laughing derisively at him. It means a “fool” or “idiot”.