Sources and explanations:
The Rivash wrote (siman 425), and it was cited as halachah by the Rema (Yoreh De’ah, siman 183): It is clear that relations with a niddah are prohibited—not only with one’s wife, but whether she is one’s wife, another man’s wife, or an unmarried woman. We learned in Keritot (14a): One who has relations once may incur six sin-offerings for it: one who has relations with his daughter is liable on account of daughter, his sister, his paternal brother’s wife, his paternal uncle’s wife, a married woman, and a niddah. Likewise, we learned in tractate Ketubot (29a): These are the young women for whom there is a fine, etc. Among them it lists one who has relations with a niddah. It concludes: Although they are punishable by karet, they do not incur a court-imposed death penalty. Even regarding a non-Jewish woman, even in private and on an occasional basis, the court of the Hasmoneans decreed that one transgresses on account of niddah, as stated in the chapter Ein Ma’amidin (36b): Although her blood is, by Torah law, like the blood of an animal. If a Jewish woman were prohibited as a niddah only to her husband, they would not have decreed regarding a non-Jewish woman where there is no marriage. This is self-evident, and no one ever doubted it. Discussion with her is permitted. Scripture likewise states without qualification: “And to a woman in the impurity of her niddah, you shall not draw near” (Vayikra 18:19), and does not distinguish between one’s wife and an unmarried woman, for it does not say, “And to your wife.” Regarding the word “woman,” they expounded in the chapter Ve’elu Hen Ha-Lokin (14a) that one is liable for each and every woman. From this verse, the Sifra derives that even mere closeness—meaning closeness for pleasure, such as embracing and kissing—is prohibited by Torah law, even without yichud, where there is no concern for relations, because the closeness itself is prohibited by this negative commandment. For it was taught there in the Sifra: “And to a woman in the impurity of her niddah, you shall not draw near to uncover her nakedness.” I know only that he may not uncover; from where do we know that he may not draw near? Therefore, the verse states, “You shall not draw near.” I know only that with a niddah there is a prohibition against drawing near and uncovering; from where do we know that regarding all forbidden relations there is a prohibition against drawing near and uncovering? Therefore, the verse states, “You shall not draw near to uncover.” End quote. The Rambam likewise wrote that one receives lashes for this by Torah law. We do not rule in accordance with Rabbi Pedat, who said in the first chapter of Shabbat (13a) that the Torah prohibited only closeness that involves uncovering nakedness. End quote.
Therefore, since the practice today is that unmarried women do not immerse, they consequently have all the laws of a niddah. They are prohibited in yichud and physical contact, and her status is that of other unmarried women.
This response was translated automatically from Hebrew and has not yet been reviewed by a person. Therefore, it may contain inaccuracies and should not be considered a definitive reference.
