The word backronym is of a course a blend of back and acronym, and seems to have been around for twenty years or so, its first use dating back to the early eighties. The back in the word relates to the linguistics term back formation. Back formation is an irregular type of word formation where a shorter word is derived by deleting an ‘imaginary’ affix from a longer word already existing in the language. For example, the verb edit is derived from the noun editor, and not the other way round, as is more conventional (compare act/actor, sing/singer).