Q I was surprised to learn that “escalate” has only been part of English since the 1940s and that it comes from the word “escalator.” How did “escalate” acquire its current meaning? – P.B., Chicago, Illinois

A: As you noted, “escalate” is a back-formation from the noun “escalator.” It was first used in the early 20th century with the literal sense, “to ride up on an escalator.” Its figurative meaning of “to increase in extent, volume, number, amount, intensity, or scope” appears to have developed from figurative uses of “escalation” and “escalator” that originated in the 1930s. “Escalation” first referred to a provision in naval treaties allowing a country the right – the “right of escalation” – to increase the size and number of its warships in order to keep up with any increase made by the other country. “Escalator” was used in describing a provision in labor contracts – an “escalator clause” – allowing for increases in wages and prices to reflect increases in costs. When “escalate” began to be used figuratively, it was also in reference to military and financial matters.

“Escalate” became a common word in the 1960s, when it was used constantly in speaking of the increasing U.S. involvement in the war in Vietnam. As its range of applications expanded, it was inevitably criticized as a vogue word, but it fared better than many other back-formations. Much of the criticism that has been directed at it has come from British sources. Several British commentators have contended that it can be appropriately used only in describing increases that occur in successive stages. But our evidence suggests that “escalate” typically implies a continuing and usually undesirable increase or expansion, often with the added implication that each stage of the increase provokes even further increases.

Q Can you explain the origin of the phrase “fly off the handle,” meaning “go into a state of sudden and violent anger”? What “handle” are people talking about? – D.A., Danville, Ill.

A: The handle in the phrase “off the handle” is the handle of an ax. In the pioneer days, axes were handmade, and the ax-heads were often crudely fitted to the helve. Thus it was not uncommon to hear of, or even see, the head of an ax flying off as the woodsman chopped away. This sudden flying off of the head of an ax and the danger that it caused eventually came to suggest the danger or trouble that comes when people suddenly lose their tempers.

The first documented use of the phrase “off the handle” is from 1825.

Q Can you tell me the origin of the phrase “den of iniquity”? – P.T., Jacksonville, Fla.

A: The phrase “den of iniquity” is used to denote a place of immoral behavior, often of a sexual nature. Its use in this way is a relatively recent development, but the roots of the phrase go back to the New Testament.

In both Mark and Matthew, Jesus condemns those who have been using the sacred temple as a marketplace, proclaiming that they have “made it a den of thieves.” The word “iniquity” appears numerous times in the Bible with the meaning of “injustice” or “sin.” To this day, writers use the word “den” to mean a place where iniquitous activities are carried out.

Despite all this, the exact idiom “den of iniquity” does not appear in written English until the 20th century. The song “In our Little Den of Iniquity” from the 1950s musical “Pal Joey” is an early example. It refers to a secret hideaway for romantic rendezvous. Used more solemnly, the expression “den of iniquity” implies a certain seaminess that a morally upright person would consider intolerable.

Q I often wonder why the words “left” and “right” became associated with the political connotations of “liberal” and “conservative.” Can you explain how or why this happened? – M.T., New York City

A: “Left,” “right” and the associated terms “leftist,” “rightist,” “left-wing” and “right-wing,” developed their political meanings from the seating arrangement of legislative bodies in continental Europe. The members who hold more conservative views than the other members generally sit on the side of the legislative chamber to the right of the presiding officer. Similarly, the members holding more radical views sit on the left side of the chamber.

The origin of the practice of seating legislators this way may stem from the custom of seating honored guests to the right of the host at a formal dinner or gathering. Members of the legislature who were nobles would have been seated to the right in recognition of their titled status. The nobles, in general, held the more conservative views, so conservatism became associated with “right” and liberal views became associated with “left.”

Q Can you explain why a certain kind of show can be called a “review” or a “revue”? Why are there two different spellings? – G.J., Newport, R.I.

A: “Revue” has only one meaning: “a theatrical production consisting typically of satirical skits, songs, and dances.” That also happens to be one of the many meanings of “review,” as in “she performed in a Broadway review.” “Review” acquired this sense from “revue,” which was the name given to these shows when they first became popular in Paris during the 19th century. The shows were – and often still are – intended to satirically review current events; hence the name “revue,” which is simply the French word for “review.” Perhaps because of this etymological connection, usage commentators are generally tolerant toward the use of “review” as a synonym (or, if you prefer, a spelling variant) of “revue,” although some critics explicitly reject the use of “review” for “revue.” Others consider “review” acceptable but prefer “revue.” So, apparently, do most writers and editors. Our evidence shows that “revue” is appreciably more common than “review” in this sense.

This column was prepared by the editors of Merriam-Webster’s Collegiate Dictionary, Tenth Edition. Readers may send questions to Merriam-Webster’s Wordwatch, P.O. Box 281, 47 Federal St., Springfield, MA 01102.