Abbreviations are used to provide a shortened form of a word or phrase. One style of abbreviation combines the initial letters of each word in a series. In cases in which the resulting abbreviation is pronounced by saying each of the letters in order, this is called initialism. An example is the abbreviation for extrasensory perception, which is ESP.
Cases in which this abbreviation is pronounced as a word in and of itself, form a different class of abbreviation, referred to as an acronym. Acronyms were first used in the 1940’s. The name comes from two Greek words, akron, meaning “end or tip,” and onumon, meaning “name.”
In order to form a pronounceable word, an acronym may leave out “little words” in the series by not providing a letter to represent them. An example is NASDAQ system. The actual phrase is: "National Association of Securities Dealers Automated Quotation System" but, as you can see, the word "of" is not represented in the acronym.
Another liberty that acronyms may take is to include an initial for each part of a compound word. Some abbreviations combine initialism with an acronym. CD-Rom, in which the first two letters are pronounced as letter names, and the last three are pronounced as if they were a word, is an example. JPEG and MS-DOS follow suit.
Another variation is the use of more than one letter from each word in order to create an acronym that is pronounceable as a word. This is true, for example with the acronym of lower power mode, which is not “lpm,” but “lopomo,” using the first two letters of each word in the sequence.
In some cases, an acronym is used so often that some people may not recognize it as an acronym. This has been known to happen with the following:
• scuba — self-contained underwater breathing apparatus
• radar — radio detecting and ranging
• laser — light amplification by stimulated emission of radiation
Posh may be the word that has caused the greatest argument in the world of the acronym. Some claim that posh is an acronym for “Port Out, Starboard Home,” reportedly the preferred seating for ship passengers traveling from England to India and home in the 1800s. This etymology is not documented and is disputed, although there is no clear and accepted alternative.