Say what? Putting aside the fact that this sounds like a whitewashed description of sexual assault, at what point in history was this "practice" so common that it was given a name?
I don't know when it started, but the word originally comes from [呼ばう]{よばう} and is more commonly written as [夜這い]{よばい}. It is an old Japanese custom that was common up until the Meiji or Taisho Period and originally was thought of as a way to propose to a girl (I use the word "propose" very loosely here). However, in very local areas, it supposedly lasted up until around World War II.
Is the definition accurate, or is it just another case of WWWJDIC and its occasionally misguided and erroneous community contributed obscure definitions?
It is misleading. The way we think of two people meeting, falling in love and getting married is very different from what went on in the olden days in Japan. There was also no concept of "cheating on your spouse", etc. the way we think of nowadays.
Basically every small village had a set of customs or rules which everyone would abide by. よばい refers to a custom were men were allowed to go to the place where a girl was sleeping, and if the girl approved, make love. Now, if the girl refused, you were supposed to leave or else the father would come and haul the guy away. However, sexual assault did occur sometimes, and よばい sometimes does implicitly imply that. Also, in some villages, if you didn't abide by the rules, there would be some kind of punishment involved.
However, every village was different. In some areas it was common for women to sneak into guys rooms, or they would hold a festival of girls (or guys) who "became of age" where older people would teach them how to have sex. Also, a lot of times you would have sex with so many different people, nobody really knew who their real father was. The examples I'm giving are just some of the customs that were present, but I'm sure there are a lot more. Also, the idea of "marriage" in Japan was when you could regularly go to a girl's house without sneaking. The word 結婚 itself didn't actually exist till the Meiji Era because there was no word to translate "marry"*
*: It should be noted that there were words that meant "becoming a couple" in Japanese, such as [婚姻]{こんいん} that existed before the word 結婚, but they didn't mean the same thing as the word "marriage" in English.
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