I’m going to have to be short with you. Don’t worry, I’m not cross with you. All I mean is that today we’re going to be looking at abbreviations — shortened forms of words and phrases.

There are various types. Let’s start with good old contractions. As you know, they’re words that either omit letters from the middle of the word, such as “Dr.” and “St.,” or use an apostrophe to mark the omission of letters, as in “can’t” and “don’t.” In formal writing, which is used by scientists and those in the medical profession among others, contractions are generally avoided with the exception of mandatory forms such as “o’clock” and “man-o-war.”

Shortenings are words that use the first few letters of a word with a period, such as “etc.” or use the stressed syllable of a word without a period, such as lab, exam and dorm. These shortenings, also known as clipped words, were often originally used by specialized groups such as scientists, and do not change the part of speech of the word being shortened.

In 1922 Danish linguist Otto Jespersen noticed that children tended to clip off the first part of a word and use the second part, while adults did the opposite. Clipping the first part of a noun gives us words such as: bot, chute, gator and phone. Clip the last part and you get words such as: ad, doc, gas, gym and memo.

Initialisms consist of the initial letters of words such as p.m., FBI, UCLA and NYC. But unlike acronyms, which are pronounced like a word — NASA and MADD, for instance — initialisms are pronounced letter by letter — including NAACP and NSA. Periods are usually omitted in initialisms that consist entirely of capital letters.

As early as 1921, the German language had the word “Akronym” (German nouns are capitalized), meaning, “new word made up of initials.” Acronyms are abbreviations that have become words that do not have periods, such as: laser, radar, DARE, Scotus, SWAT, AIDS and scuba. Acronyms of five or more letters are usually lowercase.

Interestingly, there is a distinction between acronyms and those tricks we use to remember things — such as using HOMES to remember the names of the Great Lakes — which are called mnemonic devices.

Then there’s the backronym, which was coined in a 1983 letter by Meredith G. Williams of Potomic, MD, and consists of words that are made up and later become an acronym. For example, the distress signal SOS originally didn’t stand for anything. The letters SOS were selected because they were easy to send and receive via Morse code. The meanings “save our ship” and “save our souls” were assigned to the letters later. A couple other backronyms are ZIP code and SAD.

Finally, stump compounds are shortened words that are joined together, such as reforger (reassignment of forces to Germany), defcon (defense condition), and even place names such as Bosnywash (for the Northeast corridor) and New York’s Tribeca district.

I have more, but I’ve got to go ASAP. The CIA and SWAT are looking for me, so I’m going to hide out in SOBE or perhaps NOLA. See you next week, OK?

Jim Witherell of Lewiston is a writer and lover of words whose work includes “L.L. Bean: The Man and His Company” and “Ed Muskie: Made in Maine.”