Which of the following words is an acronym? NATO, jpeg, Nabisco, radar, SAT, OMG, WTF? Most would agree that they’re all acronyms, with the possible exception of the latter two, but there are purists who would argue that only NATO fits the true definition.

There’s a whole lot of confusion out there about what actually constitutes an acronym, and there’s no elegant or eloquent way to define or explain what it is in its various incarnations (partly because of the very ambiguity of the word itself). According to Wikipedia, it’s “the name for a word from the first letters of each word in a series of words”; as Merriam-Webster explains it, acronym is “a word formed from the initial letter or letters of each of the successive parts or major parts of a compound term”. Hmmm … We’ve hardly begun, and already we’re sensing some disagreement: is it just the first letter of each word, as explained by Wikipedia, or can it be made up of more than one letter from each constituent word, as Merriam-Webster suggests? The OED goes further by qualifying that it is a word “usually pronounced as such, formed from the initial letters of other words.” Indeed, some definitions prescribe that an acronym must be pronounceable as a word (eg. NATO) in order for it to qualify as such. The most common acronyms in use today are not pronounceable/pronounced as words but are simply strings of initials (FBI, SAT, BBC, CIA, PR etc.); this form of initial-letter abbreviation is also referred to as an initialism or an alphebiticism — especially by those unwilling to confer acronym status on it.

Deriving from the Greek acro-, acron (meaning extreme, tip or end) and onoma (name), the word acronym is relatively young. It was first coined in the 20th century, and many early examples were shorthand names for organizations created during or in the aftermath of the two world wars. Anzac (Australian and New Zealand Army Corps) and Wrens (Women’s Royal Naval Service) were names for WWI units; as well as radar (radio detection and ranging), awol (absent without leave), and scuba (self-contained underwater breathing apparatus) coming out of the Second World War, a whole series of postal acronyms were developed by active servicemen conveying romantic messages to their sweethearts back home. SWALK (“sealed with a loving kiss”) is just one example of such a word scribbled on the back of many an envelope. I’m reading Erik Larson’s fabulous book about Germany in the early 1930s, In the Garden of Beasts, in which he reminds us of how the name Gestapo — the secret police of Hitler’s Nazi regime — came to be: from the first letters of its full German name “Geheime Staatspolizei”. So it wasn’t just the Americans looking to abbreviate the names of their organizations. NATO, NASA, and UNESCO are widely used true acronyms whose full multi-word original names are now almost forgotten. The machine that generates random numbers for the UK’s Premium Bond (or national lottery) drawing is called ERNIE, after the electronic random number indicator equipment.

There are no less than 84 definitions for the initialism “C.O.D.”, which is most commonly understood to mean cash on delivery. If it were a pure acronym it would be pronounced “cod”, and this brings us to another factor in the “what makes an acronym” argument: whether said abbreviation is spoken or written, and in what context. Especially now in our ADD world of SMSs, IMs, AIMs, texts, and tweets, where brevity is king, acronyms or initialisms are invading the language. BRB (be right back), LOL (laugh out loud), BTW (by the way), OMG, and WTF are just a few of the ubiquitous acronyms that populate the vast new vocabulary of internet slang. But these initialisms are rarely spoken aloud, since the number of syllables used to pronounce the full phrase is usually no greater than that of the acronym itself (and in the case of WTF, the initialism is actually longer and harder to pronounce than the words it represents), and therefore are used predominantly for keystroke- and character-saving purposes. So this particular form of acronym tends to be reserved for the pen or the keyboard — and many would argue that this confined usage and function strips the abbreviation of its acronym status. However, it’s worth noting that these written abbreviations existed long before keyboards became our predominant tool for writing: FYI (for your information), IMO (in my opinion) and P.S. (postscript) have been in the written vernacular for a long time, and some Latin acronyms even pre-date modern English: a.m. is from the Latin ante meridiem (“before noon”), and p.m. is post meridiem; A.D. (from the Latin Anno Domini, “in the year of our Lord”) was soon complemented by the English-sourced B.C. (“before Christ”).

OK is used and understood all over the world with its meaning of approval, assent, acceptance, agreement or acknowledgement. No-one really knows where OK originates, but the many theories of its etymology — a number of which have been dismissed as false — are acronym-based. Here are a few of them, all dating from the 19th century:

• initials of “oll korrect”, coined  during a Boston fad for comical misspellings and abbreviations
• initials of “Old Kinderhook”, the nickname for Martin Van Buren, used as a slogan in the 1840 presidential election
• (German, c. 1900) initials of ohne Korrektur (“without correction”)
• (Greek) initials of Ola Kala ( Ὅλα Καλά, “everything is fine”), used by teachers marking students’ work
• initials of “Open Key”: a global telegraph signal meaning “ready to transmit”
• (Latin) initials of Omnis Korrecta (“all correct”), used by early schoolmasters marking examination papersoch aye (“ah, yes”) used by Scottish immigrants