A backronym (or bacronym) is a phrase that is constructed "after the fact" from a previously existing abbreviation, the abbreviation being an initialism or an acronym. The term is sometimes used to refer to the initialism or acronym itself,
but usually in those cases, it is a "replacement" backronym, the abbreviation already having an associated phrase. When the backronym phrase becomes more popular than the original, the word becomes an anacronym.
