Q. Why is the surface of an airport runway called a "tarmac"?A. The word "Tarmac" is a trademark for a bituminous bind-er used to pave roads. In this use, it is properly capitalized. Before "Tarmac," there was a generic word, "tarmacadam," formed by combining "tar" with "macadam." Macadam, which is named after 19-century British engineer John L. McAdam, is roadway or pavement that is finished by a process of compacting into a solid mass a layer of small broken stone on a convex, well-drained roadbed using a binder (something that makes the mass cohesive). This makes the road surface much smoother and safer for driving. Adding tar to macadam makes the surface waterproof as well. Since airplanes must take off and land in all sorts of weather, airport runways are often paved with tarmacadam, as are public roads and highways.
Around 1926, the word "tarmac" came into general use as another name for a tarmacadam pavement, whether a road, apron, or runway. In fact, airport runways are so often made in this way that "tarmac" is sometimes used as a synonym for "airport runway," as in this example from our files: "Passengers were made to identify their luggage on the tarmac before it was allowed into the terminal or on the plane."
Q. Can you settle a dispute? My wife says that "erupt" can be spelled "irrupt." But "irrupt" is a misspelling of "erupt," right?
A. Not exactly. "Irrupt" is not a variant spelling of "erupt," but it is a legitimate word in its own right. "Erupt" and "irrupt" have existed as discrete words since at least the mid-1500s. Both are descendants of the Latin verb "rumpere," which means "to break," but "irrupt" was formed by adding the prefix "ir-" (in the sense "into") while "erupt" was formed by adding "e-" (meaning "out"). So "to irrupt" in its oldest and etymologically most accurate sense means "to rush in," and "to erupt" means "to rush out." Because of their similarity in form and pronunciation, and perhaps also because it's sometimes hard to distinguish the precise direction of a violent rush, the two words have been used as occasional synonyms for at least the last 400 years. In current English, though, "irrupt" is a much less common word that "erupt," and its use is largely limited to its original "rush in" sense.
Q. The phrases "they may be one and the same" and "they may be one in the same" - which is correct?
A. "One and the same" is clearly the original and usual phrase, and it is also certainly the more logical phrase. However, "one in the same" does appear in published writing on occasion, and it may be approaching established usage.
"One and the same" is simply a more emphatic form of "the same." It is formed along the lines of "each and every" and "any and all," phrases that have frequently been condemned as redundant or trite by language commentators but that are often found useful by the rest of us. So far, "one in the same," which plays the same emphatic role, seems to have avoided the critics' attention. "One in the same" presumably developed from a misunder-standing of the original phrase, reflecting the fact that, in ordinary speech, "one and the same" and "one in the same" sound identical.
"One and the same" has been employed by writers since at least the middle of the last century. We can't say for sure when "one in the same" got started, although the earliest examples of it in print that have so far surfaced are less than 20 years old.