An idiom is a phrase whose meaning isn't necessarily obvious from a first glance at the individual words.

We've all heard and even used the phrase, "let the cat out of the bag," but ... do we even know what it means? And no, it doesn't actually mean that a cat is being kept in a bag, 'cause that's just, well ... ridiculous.

That phrase is an "idiom," and there are plenty more just like it in the English language. According to Merriam-Webster, an idiom is "an expression in the usage of a language that is peculiar to itself either in having a meaning that cannot be derived from the conjoined meanings of its elements (such as up in the air for "undecided") or in its grammatically atypical use of words (such as give way)."

So, in order to help give some clarity, we've scoured the internet and found 15 of the most popular idioms in the English language and their meanings.

15 Most-Popular Idioms and Their Meanings:

*All meanings and definitions are taken directly from the Cambridge Dictionary.

• A Blessing in Disguise
  • "Something that seems bad or unlucky at first, but results in something good happening later."
• Beat a Dead Horse
  • "To waste effort on something when there is no chance of succeeding."
• Bite the Bullet
  • "To force yourself to do something unpleasant or difficult, or to be brave in a difficult situation."
• The Best of Both Worlds
  • "A situation in which you can enjoy the advantages of two very different things at the same time."

• Don’t Count Your Chickens Before They Hatch
  • "You should not make plans that depend on something good happening before you know that it has actually happened."
• Costs an Arm and a Leg
  • "To be very expensive."
• The Elephant in the Room
  • "An obvious problem that no one wants to discuss."
• Fit as a Fiddle
  • "To be very healthy and strong."
• Hit the Nail on the Head
  • "To describe exactly what is causing a situation or problem."
• Let the Cat Out of the Bag
  • "To allow a secret to be known, usually without intending to."
• A Piece of Cake
  • "Something that is very easy to do."

• Once in a Blue Moon
  • "Not very often."
• (Straight) From the Horse’s Mouth
  • "If you hear something (straight) from the horse's mouth, you hear it from the person who has direct personal knowledge of it."
• Under the Weather
  • "If someone is or feels under the weather, he or she does not feel well."
• Wild-Goose Chase
  • "A search that is completely unsuccessful and a waste of time because the person or thing being searched for does not exist or is somewhere else."

How many of the above phrases have you been using correctly, or incorrectly? Are there any popular idioms that we missed on our list? Email us!