This list is incomplete; you can help by expanding it (http://en.wikipedia.org/w/index.php?title=List_of_idioms_in_the_English_language&action=edit).
A list of idioms can be useful, since the meaning of idioms can not always be deduced by knowing the meaning of the individual words that make them up. For example, someone could know what a bucket is and also know what to kick something means, but they might not know that to kick the bucket means to die.
Note that idioms are not the same as proverbs, which are usually statements ("a bird in the hand is worth two in the bush") or directives ("don't count your chickens before they hatch").
Here is a list of idioms in the English language along with their meanings:
A black look: Giving someone a look of malice; "a dirty look"
A tempest in a teapot: A fuss being made about an insignificant matter.
Arm and a leg (to pay): An extremely high price.
Bad: Very good.
Ball and chain:
An unhelpful burden that cannot be abandoned;
Husband or wife (pejorative).
Bat out of Hell (like a): Very quickly (also implies haphazardly, frenetically or in a panic).
To bear fruit: To come to profitable conclusion or to produce some worthwhile thing.
Beat a dead horse:Beating a dead horse is to engage in pointless and repetitive discussion. Beating is more common in American idiom, while Flogging a dead horse is more common in British idiom.
Beat around the bush: Procrastinate or hesitate, mainly when one does not want to say something. (see circumlocution).
Being from Missouri: Skeptical; requiring proof. (The state's unofficial slogan: "Show me" appears on their license plates.)
Between a rock and a hard place: When you are "between a rock and a hard place" you are in a very difficult jam, any resolution of which, regardless of which resolution, will not be pleasant. Another common form of this idiom is "between the Devil and the deep blue sea."
Black-hearted: Someone with evil intentions.
Black sheep: An ostracized or ill-fitting member of a family or group. ("Uncle Ned is the black sheep of the family.")
Boot out: To eject a person from a group or society against their wishes.
Break a leg: Good luck, especially used to wish luck to stage performers before an opening.
Broken his duck: (British), "scored for the first time," or more generally to have avoided complete failure. In British sports slang a "duck's egg" refers to a score of "zero" or "naught". (Similarly "goose eggs" can also mean "00" in American slang.) In the British game of Cricket scoring naught is getting a "duck" and a batter's first run scored is, therefore, "breaking his duck." Generally intended hopefully, as a harbinger of more success to follow. "He's out of his rut and starting to make progress."
Bull in a china shop: A person with no tact who upsets others or upsets plans; a very clumsy person.
Burning the candle at both ends: Someone who has too much going on, wearing themselves out.
Burning the midnight oil: Study or work late until night.
Buy the farm: To die (possibly a cynical reference to the effect of a life insurance benefits to the beneficiaries; as in "his demise bought the farm").
Buying a pig in a poke: To purchase something without inspection, thereby creating an opportunity for fraud. Canonical: unethical farmer places a barn-yard cat in a burlap bag (poke) and sells it sight-unseen to another, claiming it contains a piglet. Related to "the cat's out of the bag", below.
by the numbers: to do things precisely as instructed, or as perceived to be instructed.
Can of worms: A situation that is hard to deal with, especially one that comes about unexpectedly and intractably. To "open a can of worms" is to get involved with something that is unsightly, unpleasant and not easily escaped (closing a container of worms, used as bait by fishermen, generally involves some tricky handling of the wriggling occupants).
Can't see the forest (or wood) for the trees: Losing sight of the big picture by getting mired down in details.
Can't see your nose in front of your face: Being oblivious to something in plain view.
Cat got your tongue?: Asked of someone rendered speechless to emphasize their inability to speak.
Cat nap: A short sleep taken during the day. However, this may not necessarily qualify as an "idiom", as the meaning is apparent to some; cats tend to sleep for short intervals (naps) at various times throughout a twenty-four hour period, whereas humans generally sleep for a solid one-third fraction of each day and do not typically "nap" in a catlike manner. Thus, sleeping in this manner is to "nap like a cat", or to take a "cat nap".
Change horses in midstream: Make new plans or choose a new leader in the middle of an important activity. Connotes an unwise, or at best risky, activity.
Close the barn door after the horse gets out: Refers to not taking action until after a problem has already occurred, usually when it's too late and should have been done sooner.
Crash: To go to sleep
Cut off your nose to spite your face: To take rash or single-minded action that hurts your own cause in the end.
Dark horse: A surprise candidate, or competitor. From the metaphor: "He rode in as if on a dark horse in the night" or "No one saw him coming."
Dead and buried: A settled issue. Something no longer needing consideration.
Dead as a doornail: Useless, very distinctly dead. A doornail is the strikeplate for most door knockers. To hold it in place, after it was driven through the door, the pointed end was bent over and buried in the door, to prevent movement. This nail was unrecoverable, so was considered dead to future reclamation, which was apparently common before modern time.
Devil's advocate: To argue a point of view that is not necessarily one's own, but for the sake of fairness. To play "the devil's advocate" in a debate is to ensure that some attempt was made to hear a side that might otherwise have gone unrepresented.
Dog and pony show: A presentation which aims to persuade, generally a marketing presentation, especially one with lots of splashy glitz and little or no real informational content.
Have a dog in the fight: To have a stake in the outcome of the problem at hand. Conversely, "I don't have a dog in that fight" is frequently used as a way to beg off and opt out of being expected to assist. People who live in San Diego do not "have a dog in the fight" as to who will be the next Police Commissioner of Boston.
Have one's cake and eat it too: To attempt to get all the positive aspects of something while avoiding any negative but usually occurring aspects.
Fall on (one's) sword: To take responsibility or blame for a negative outcome, especially if one's own idea.
Feel blue: Feeling sad, down, or depressed.
(On a) fishing expedition: Trying to find some evidence of something, often through improper methods. Sometimes used in court.
Five finger discount: To take without paying, to steal. (Also known as shoplifting.)
(Bird in a) Gilded cage: In a pleasant situation, but trapped. For example, celebrities that fear the paparazzi are "prisoners in gilded cages," because despite their wealth and fame their every action is under intense scrutiny.
Herding cats: Trying to elicit coordinated action from a group not inclined to do so. Doing something that is very difficult.
Hit the hay: To go to bed.
Juggling picked onions: carrying out a hazardous/difficult task.
Keep a stiff upper lip: To exercise self-restraint in the expression of emotion, especially fear or grief.
Kick the bucket: To die. Derived from the slaughter of pigs, the wooden block a pig was hung from during slaughter was referred to as a buque. Thus in the process of killing the pig, it would inevitably kick it.
Killing two birds with one stone: Completing two tasks with one process or action.
Last straw: A problem or obstacle that may be trivial in itself, but causes cataclysmic failure because it pushes the total array of problems or obstacles to an intolerable level. Also referred to as the Straw that broke the camel's back, after the original proverb: a straw by itself has an insignificant weight, but enough of them together can be a crushing weight.
(the) Lights are on, but no one's home: The person that is referred to is lacking intellect and/or sanity, even if they may appear at first to possess full mental faculties. Like "two bricks short of a load", there are endless variations, based around the metaphor of a machine or a system that is not operating as it should ("His elevator doesn't stop at all floors.")
Loan shark: A predatory lender, usually one that charges inordinately high interest.
Not playing with a full deck: Someone who is eccentric, mad or wildly unconventional, bordering on crazy. See Two bricks short of a load on this page.
Used to express displeasure, either as a general interjection ("Nuts!") or directed at a person or thing ("Nuts to you!"). (See: Battle of the Bulge)
Over the hill: To be past one's prime, old, a senior citizen. A person has reached his/her peak of physical or employment capabilities and is starting the downhill slide.
Pay through the nose (for something): pay too much or a lot of money for something.
Pot calling the kettle black: Where person A accuses person B of something that person A is guilty of. Usually implies that person A should ideally not accuse while he/she is guilty of the same thing.
Push up daisies: To be dead. (example: He's pushing up daisies.) This comes from the western cultural practice of burying the deceased in a cemetery or "memorial park" and of growing flowers or grass over their grave.
Reading between the lines: Inferring information not explicitly stated.
Red light district: An area of town where one will find a proliferation of prostitutes, strip bars, pornography and sex toy shops, and the like.
Red tape: Bureaucratic paperwork, usually in large amounts and being difficult to finish yet seemingly pointless in nature.
Right under your nose: Something so obvious that it is easily overlooked.
Rob Peter to pay Paul: Solving a problem in a way that leads to a new problem; a quick solution with an obvious drawback.
Rooted to the spot: One that has not moved out of the place where the person has been for a long time. Both in physical, and in mental situations.
Six feet under: Dead and buried (from a traditional depth for human graves).
Six of one, half-a-dozen of another: Two things that are essentially the same and so there is no real choice to be made.
Soup to Nuts: From beginning to end. IE from the first course of a meal to the last course.
Sour grapes: To decide that the attainment of something you have been thwarted from getting is not worth it after all and probably inferior in quality anyway. (Aesop's Fables: The Fox and the Grapes)
Spinning a yarn: To tell a story, especially one with distorted truths or exaggerations.
Spirit of the Law: To interpret something as it is meant, not as explicitly stated.
Straw that broke the camel's back: From a proverb about loading up a camel beyond its capacity to move. This is a reference to any process by which cataclysmic failure (a broken back) is achieved by a seemingly inconsequential addition (a single straw). This also gives rise to the phrase "the last straw."
Swan song: A final appearance; a theatrical or dramatic farewell (from a legendary belief that swan would sing its own dirge as they died)
Swim with the fishes: To die, especially to be murdered and have your body disposed of, often in a body of water. (See also "sleeping with the fish"). It's presumed to be a bit of mobjargon.
Sword of Damocles: The Sword of Damocles is a frequently used symbolic allusion to this myth, referring to the insecurity felt by those with great power due to the possibility of that power being taken away suddenly, or, more generally, any feeling of impending doom.
Take a flyer: To take a chance or risk.
Take a seat: A command to sit down
Taken to the cleaners: Defrauded, robbed, cheated, conned.
Tall tale: A (sometimes boastful) unrealistic story, often told in a humorous way.
The cat's out of the bag:To let the cat out of the bag A secret or hidden thing has been discovered. Related to "buying a pig in a poke", above.
The Powers That Be: Generic term for people who are in charge of something. Often used either derisively or when the actual people are not known. Usually capitalized.
((The) tail that) wag(s) the dog: To note or have an out of porportion impact or influence. "He is addicted to Wikipedia, it's the tail that wags the dog." To note reversal of a typical or expected causality chain, usually in exclamation. "That bird frightened the cat! Doesn't that just wag the dog!"
Three sheets to the wind: Drunk.
To be catty: To be antagonistic, usually applied to women.
To pocket: To attempt to steal by slipping something unnoticed into a concealed place (pocket, purse, jacket, etc.).
To turn turtle: To capsize.
toot your own horn:to brag about yourself
Toe the line: To follow rules and regulations faithfully. To be careful to never commit any transgressions. To conform, particularly to conform to onerous or odious demands through loyalty.
Two bricks short of a load: Not possessing all of one's mental faculties; i.e., crazy or stupid. AKA "two bricks shy of a load". The general form "N Xs short of a Y", where N is a small number and X is an item in a set Y, provides endless recognizable variations. Examples: "two chairs short of a set" (Gilmore Girls, "Emily in Wonderland"); "One Can Short of a 6 Pack" (Da Yoopers album); "two deuces shy of a deck" (playing cards) (see "Not playing with a full deck").
Up a creek without a paddle: To be in an untenable position. To have no recourse.
Water under the bridge: Something that has happened in the past and is no longer worth agonizing over. A dismissal of prior offenses or transgressions. Generally said after emotional conflicts.
A few fries short of a Happy Meal:* See "Two bricks short of a load"
An idiom is a phrase where the words together have a meaning that is different from the dictionary definitions of the individual words, which can make idioms hard for ESL students and learners to understand.
This idiom, coined by John F Kennedy, describes the idea that when an economy is performing well, all people will benefit from it.
When this idiom is used, it is a way of allowing an older person to do something first, though often in a slightly sarcastic way.