Backronym

backronym

noun [bak-ruh-nim]

1. an existing word turned into an acronym by creating an apt phrase whose initial letters match the word, as to help remember it or offer a theory of its origin. For example, rap has been said to be a backronym of “rhythm and poetry.”
2. the phrase itself. For example, “port out, starboard home” is a misleading backronym for posh.