What are some of the earliest acronyms and did they know it was an acronym at the time?
Here is an old one:
You may know that the emblem of paleo-Christians was the fish. The Greek word for the fish is "ἰχθύς" (Ichthys). And here is what it stands for if you are one of the first Christians.
- I (I, Iota) : ΙΗΣΟΥΣ (Iêsoûs) « Jesus »
- Χ (KH, Khi) : ΧΡΙΣΤΟΣ (Khristòs) « Christ » ;
- Θ (TH, Theta) : ΘΕΟΥ (Theoû) « God » ;
- Υ (U, Upsilon) : ΥΙΟΣ (Huiòs) « Son » ;
- Σ (S, Sigma) : ΣΩΤΗΡ (Sôtếr) « Saver ».
And on the same theme, the acronym INRI (so often seen on crucifixes), but Latin this time:
- I : IESVS : Jesus
- N : NAZARENVS : Nazarene
- R : REX : King
- I : IVDÆORVM : of the Jews
As you can see, acronyms are no recent invention. As for what was the first one, this is probably lost forever.
In Douglas Harper's rebuke, '"shit" is not an acronym', he writes that acronyms are very modern inventions. They were found in World War I, but still weren't the preferred way of abbreviation. Their use really took off and became common during World War II, and really accelerated during the cold war and US space programme.
He also notes the use of acrostics, a poem or puzzle such as cabal, where the first initial of an existing word is made of other significant words. However, Harper argues this wordplay had been around for centuries and they aren't really acronyms: the root word already existed and no-one was pretending the initials were the source.
Read the interesting article for more, here's a brief snippet:
Acronyms didn't becom a common method of word formation in English until World War II. The word acronym itself wasn't coined until 1943. The lack of a need for such a word suggests the degree to which acronyms previously were not a part of daily life. Their use accelerated with the U.S. space program and the Cold War, and by the time a "Dictionary of Acronyms, Initialisms and Abbreviations" was published in 1960 it had 12,000 entries.
So acronyms in English are on the whole a 20th century phenomenon. Among those with pre-1900 origins are A.D. and B.C. (both Latin) and P.D.Q. (1870s). The word OK (c.1839) is another rare exception (if the most accepted theory of its origins is the right one), as is n.g. for "no good" (1838). And note how these initialisms, even after more than 170 years, are still "felt" as abbreviations, pronounced as distinct letters, and require no elaborate Internet stories.
As you might expect, the use of acronyms themselves long predate the coinage of the term.
For example, from Wikipedia: "Initialisms were used in Rome before the Christian era. For example, the official name for the Roman Empire, and the Republic before it, was abbreviated as SPQR (Senatus Populusque Romanus)."