Etymology is the study of the origin of a word and the historical development of it’s meaning. My question for the day, how do they know?

Sometimes it’s obvious. Let’s take the example of military terms. “Got your back” is bandied about so freely that the words run together. In 2011, when President Obama visited the Australians he said we Americans and Aussies “have got each other’s backs.” Now it seems as if every day some politician assures us citizens of the same.

Anyone can see that the image comes from comrades in arms, the brave individual charging into danger, the loyal ally guarding from the rear. For a more colorful version, a writer might use, “Got your six.” That term allegedly originated with World War I fighter pilots, making reference to the rear of the airplane as the six o’clock position, the twelve o’clock position being directly in front. On the battlefield, your six is your most vulnerable position. Another variation is the warning to “check six,” meaning, “look out behind you,” or more generally, “watch your ass!”

Other items on the list of military slang, Haji, used as a derogatory term for the enemy, adapted from the Arabic word meaning a person who has made the pilgrimage to mecca, frosty to mean alert and watchful, and “Whisky Tango Foxtrot” the military alphabet for “what the F***?” (One of those military acronyms made it all the way to the dictionaries: snafu was military slang for “situation normal, all fucked up.”)

The phrase, “balls to the wall” meaning “as fast as you can go,” sounds like a sexual metaphor, but it has to do with the design of military aircraft. The throttle has a ball-like grip at the top. For full speed ahead, the pilot pushes the control forward until it touches the firewall. Though there’s no raunchy origin, I probably won’t use that one.

Writers love the specialized vocabulary that gives a character an authentic voice, be it a sun kissed “Valley Girl” or a hard-boiled detective. One might use a bit of that kind of slang mentioned above, but too much would be obtrusive. I’d love to let a character with a military background use the term “evolution,” for some operation or activity. Examples: “No talking is required for this evolution.” Or “all hands on deck for the refueling evolution.” We know what it means, but it’s eccentric enough to suggest that we’re in a unique setting.

Etymology of sayings like these seems easy. They’re contemporary. Some living military personnel reported the use and it made it into a slang dictionary.

What about sayings that aren’t in anybody’s dictionary? How do our experts know where they came from? Some say the phrase “the whole nine yards” has a military origin, referring to the length of ammunition belts in World War II aircraft. When the gunner shot off the whole nine yards, he had exhausted his resources. Sounds good, but experts say this one is not so easy to track down. William Safire, the long time language columnist for The New York Times, thought the phrase probably referred to the capacity of a cement truck, as measured in cubic yards. He wasn’t sure. He considered it “one of the greatest etymological mysteries of our time.” That was in 1982 and things have changed.

Finding the first written use of the word or phrase seems to be the key for many experts. In Safire’s day, lexicographers did their research via manual labor, poring over old dictionaries, random books and newspaper microfiche. But this is how they do it now: search Google Books and Google News Archive, using variants of the search term.

At least, that’s how one amateur, Bonnie Taylor-Blake, found a 1921 story about a baseball game. The headline read, “The Whole Six Yards of It.” The story didn’t clarify what the headline meant, but it wasn’t an isolated use. Even earlier examples were discovered in newspaper articles that promised to tell “the whole six yards” of a story. It was a variant of the same expression, meaning the same thing it means today, “the whole thing.”

What does this discovery mean for the “etymological mystery of our time?” As a matter of logic, it refutes the theories about artillery belts and cement trucks. Those items didn’t exist when the term was used in the 1920s. What about the numbers? The switch from six yards to nine suggests that the numbers are meaningless. (Our image of “cloud nine” used to be “cloud seven” in the early part of the twentieth century.) Since we mention a specific number, but we don’t have any explanatory words like cloth or cement, we don’t know “yards of what?” Geoff Nunberg, writing for National Public Radio, suggests that the incomplete image resonates without resolving anything.

After the opening words, “The whole….” what follows could be as nonsensical as similar phrases like “the whole shebang,” “the whole enchilada,” or “the whole ball of wax.”

Nunberg suggests that we accept the mysterious saying as we would a poetic image, one that bubbles up straight from the imagination, without need for backstory or explanation.

What? Give up the search for the origin? I doubt that the amateur lexicographers, now armed with the power of the laptop, will be so easily discouraged.