A recursive acronym is one where the original term (acronym) appears as an element in the expansion of the original term; i.e. the expansion in theory goes on forever. They were a bit of charming whimsy that appeared at MIT (possibly first in the jargon term 'mung' - 'mung until no good'). The name of the text editor EINE ('EINE is not EMACS') as an early example, and for a while it was the fashion there to name editors with such names. The practise was not restricted to editors, though; for example, the Nimrod routing architecture had a recursive acronym ('Nimrod: It Might Run One Day') - although in that case it was a 'backronym' (the name existed before the expansion was created).