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about face, to do an To reverse a decision or change one's opinion. The term comes from the American military command to turn 180 degrees at attention, dating from the mid-nineteenth century, and by 1900 was being used figuratively. A more recent colloquial usage is to do a 180, but it has not yet reached cliché status.

about the size of it An approximately accurate version of a situation, event, or circumstance. It generally is used as a summing up: "That's about the size of it."

absence makes the heart grow fonder A separation enhances love. This counterpart of familiarity breeds contempt first appeared in an anthology of poems published in 1602 (it was the first line of an anonymous poem), but it was more or less ignored until it reappeared in 1850 as the last line of a song, "The Isle of Beauty," by T. Haynes Bayly. Within the next half-century it was used so much that by 1900 it was a threadbare cliché.

"You're a dedicated swallower of fascism You're an accident waiting to happen."

— Billy Bragg

accident waiting to happen, an A recipe for disaster. The phrase is used for such diverse circumstances as a large pothole causing an auto accident, an airplane flight on a collision course, or a small leak that ends in a billion-dollar oil spill like that in the Gulf of Mexico in 2010. It appears in the lyrics of several popular songs, such as the one quoted above.

according to Hoyle On highest authority, in keeping with established rules. Edmond Hoyle, an Englishman born in 1679 and buried in 1769, wrote short treatises on five different card games (they were bound together in one volume in 1746). Within a year his name appeared on other books published by plagiarists, which also gave rules and advice for playing games. This practice has continued to the present day, and there are rule books about poker and numerous other games, all invoking the authority of Hoyle, who died long before these games were invented.

AC/DC Bisexual, that is, sexually attracted to and/or active with both men and women. Originally an abbreviation for alternating current/direct current, the term has been used jokingly since the mid-1900s. Also the name of the Australian rock band, formed in 1973, that is one of the highest grossing bands of all time.

ace in the hole A hidden advantage. In stud poker the dealer gives each player a card facedown, called a "hole card"; from that point on all other cards are dealt faceup. Should the hole card be an ace, a high card, the player has an advantage unknown to his opponents. Stud poker was first introduced shortly after the Civil War and played mostly in what is now the Midwest but then was the West. In time "ace in the hole" became western slang for a hidden weapon, such as a gun carried in a shoulder holster, and by the early 1920s it was used figuratively for any hidden leverage. The related ace up one's sleeve comes from the practice of dishonest gamblers who would hide a winning card in just this way. See also up one's sleeve.

Achilles' heel A vulnerable or weak spot. The term is derived from the Greek myth of the hero Achilles, whose mother held him by the heel while dipping him into the River Styx to make him immortal. He eventually was killed by an arrow shot into his heel. The term became a literary metaphor about two centuries ago and remains current as a cliché.

acid test, the A conclusive trial to establish the truth or worth of something or someone. The term comes from a test long used to distinguish gold from copper or some other metal. Most corrosive acids do not affect gold, but a solution of nitric acid and hydrochloric acid dissolves the metal. Used literally by jewelers in the late nineteenth century, the term soon was employed figuratively, by U.S. president Woodrow Wilson among others.

across the board Affecting all classes and categories. The term, originally American, comes from horse-racing, where a bet covering all winning possibilities — win (first place), place (second place), or show (third place) — was so described. By about 1950 it was extended to other situations, principally of an economic nature, as in across-the-board wage increases (for all employees), tax reductions (for all brackets), air-fare increases, and the like.

actions speak louder than words What you do is more important than what you say. A proverb appearing in ancient Greek as well as in practically every modern language, this precise wording dates from the nineteenth century. A fifteenth-century version was "A man ought not to be deemed by his wordes, but by his works" (Dictes and Sayenges of the Philosophirs, 1477).

act your age Don't be childish or act foolish. This admonition appears to date from the 1920s. "Be your age" is the caption of a 1925 New Yorker cartoon; "act your age" appears in a 1932 issue of American Speech, a journal that chronicles current usage.

add fuel to the fire/flames, to To exacerbate an already inflammatory situation, increasing anger or hostility. The Roman historian Livy used this turn of phrase (in Latin) nearly two thousand years ago, and it was repeated (in English) by numerous writers thereafter, among them John Milton (Samson Agonistes, 1671): "He's gone, and who knows how he may report thy words by adding fuel to the flame."

add insult to injury, to To make harm worse by adding humiliation. The phrase has been traced to a Greek fable about a bald man. Trying to kill a fly on his head, he misses and hits himself very hard, and the fly replies, "You wanted to kill me for merely landing on you; what will you do to yourself now that you have added insult to injury?" It has since been applied to countless situations by as many writers, and has long been a cliché.

a dog's age A long time. An American slang term dating from about 1830, this expression doesn't make a great deal of sense, since the average dog is not especially long-lived. It appeared in print in 1836: "That blamed line gale has kept me in bilboes such a dog's age" (Knickerbocker magazine).

a dog's life Miserable circumstances. The term has been traced to Erasmus, who pointed out the wretched subservient existence of dogs in the mid-sixteenth century, as well as to the seventeenth-century proverb, "It's a dog's life, hunger and ease." It was certainly a cliché by the time Rudyard Kipling (A Diversity of Creatures, 1899) wrote, "Politics are not my concern. ... They impressed me as a dog's life without a dog's decencies." See also die like a dog.

afraid of one's own shadow Extremely timid, excessively fearful. In Richard III (ca. 1513), Sir Thomas More wrote, "Who may lette her feare her owne shadowe," although a few years later Erasmus cited Plato as having said the same thing in Greek hundreds of years before. Henry David Thoreau used the phrase to...