"Some people have asked me why I call myself a former nun when I never made vows. According to "The Catholic Encyclopedia," if a monk or a nun has been accepted by a religious order (which I was) and has been given a religious habit (which I wore), then he or she is a monk or a nun in the broad sense of the term. [Note 1] So I refer to myself as a former nun."
Note 1. "Novice" in the 1913 edition of "The Catholic Encyclopedia," Volume XI. This article is available on-line. The term "novice" refers to both monks and nuns who go through a period of training and preparation. In Section II, "Juridical Condition," the article states that a novice in a religious order is a "regular" in the widest sense of the word. (A "regular" is a technical term for a monk or a nun.)
NOTE: The article often speaks of "he" when modern usage would be to say "he or she". Section I, "Definition and Requirements,"specifically mentions nuns. And it gives instructions regarding married women who want to become nuns. So the article is about both novice monks and novice nuns.
So there you have it!