"Aidle" is the yiddish word for "sweet", with implications of "good", "nice", and "innocent". It is an adjective describing a person. The term "aidle maidle" means "a sweet girl".

In the circles where I travel "aidle" can be used as a noun as well as an adjective, and it is definitely perjorative. It means a person who is religious, god-fearing, rule-following, and often utterly boring.