Backronym

We have heard of acronym, but this is something many have unheard of Backronym (or bacronym or also retronym)

It is a phrase that is constructed "after the fact" from a previously existing word or abbreviation, the abbreviation being an initialism or an acronym. Backronyms can be classified along various types. Note that these types are not all exclusive of each other, that is, a backronym can be mnemonic, pure, and recursive.

Pure Backronyms - It occurs when the root word was not previously or commonly known as an acronym or abbreviation Eg) Adidas has been written about in All Day I Dream About Sports: The Story of the Adidas Brand. Adidas comes from the name of the shoe company's founder, Adolf Dassler, whose nickname was Adi (Dassler).

Replacement Backronyms: Some backronyms are back-formed from an initialism or acronym that is an abbreviation with another meaning Eg) IBM is the official abbreviation for "International Business Machines", but is sometimes jokingly referred to as "I've been moved", used among many IBM employees because of the frequent position changes within the company

A recursive backronym:It is an abbreviation that refers to itself in the expression for which it stands. Eg) VISA — Visa International Service Association


Apronym

Many backronyms are apronyms, that is, the word itself is relevant to its associated phrase.[18] The relevance may be either serious or ironic.
Eg) The term BASE jumping, which was coined to signify a parachute jump from one of the bases building, antenna, span, or earth.

Anacronym

Some backronyms are replacements of other phrases that have become obsolete, either for technological, political or marketing reasons. The result is an anacronym.
Eg) DVDs were originally designed as media for audio-visual data, and as such the abbreviation originally stood for "Digital Video Disc". As the format inevitably came into common use for other data storage, a different semi-official expansion was created, namely "Digital Versatile Disc". However, "DVD" officially does not stand for anything.

Mohan Rao.