Gemara

If a man does not protest when he sees his wife go out with uncovered hair, weave in public with her elbows exposed, or bathe where men bathe, he is a Rasha. It is a Mitzvah to divorce such a woman.

Kesuvos 72a (Mishnah): A woman is divorced without a Kesuvah for Overes Al (transgressing) Das. Overes Al Das Yehudis is going out with her head uncovered, spinning in the market, or talking with every man.

Aba Sha'ul says, it is even one who curses his ancestors in front of him;

R. Tarfon says, it is even a loud-voiced woman.

This is when neighbors hear her when she speaks in her house.

Question (Tana d'Vei R. Yishmael): "He will uncover her hair" warns (married) Benos Yisrael not to go out with uncovered hair. (This is mid'Oraisa!)

Answer: Mid'Oraisa, Kalasah (a basket that can be worn on the head) suffices. This does not fulfill Das Yehudis.

(R. Asi): Kalasah suffices (even for Das Yehudis).

Question (R. Zeira): In the market this does not suffice. He cannot discuss in the Chatzer (courtyard), for no Bas Yisrael is careful about this!

Answer (Abaye): It suffices in the Mavoy (alleyway), between Chatzeros.

(Mishnah): She spins in the market.

Opinion #1 (Rav Yehudah): The case is, she reveals her arms to men.

Opinion #2 (Rav Chisda): She spins with a rose by her face.

(Mishnah): She speaks with all men.

(Rav Yehudah): She jests with Bochurim (young men).

(Rabah bar bar Chanah): Rav Ukva saw an Araviya spinning, with a rose by her face. She threw her stick, and asked him to retrieve it. He made a remark.

Ravina: He said that this is spinning in the market.

Rabanan: He said that this is speaking with all men.

(Mishnah - Aba Sha'ul): Even if she curses his ancestors in front of him...

(Rav Yehudah): This is (even) if she curses his ancestors in front of his children.

(Mishnah - R. Tarfon): Even a loud-voiced woman...

(Rav Yehudah): This is one who audibly asks for Bi'ah.

101a (Beraisa): One who 'leaves without a Kesuvah', e.g. Overes Al Das and accompanying cases, does not receive Tosefes, and surely not 100 or 200.

Rishonim

The Rif and Rosh (Kesuvos 32b and 7:9) bring the Gemara in Kesuvos.

Ran (DH mid'Oraisa): The Torah uncovers a Sotah's hair to disgrace her Midah k'Neged Midah for uncovering her hair for the Bo'el. This shows that this is forbidden. Alternatively, since it says to uncover her hair, we infer that until now it was covered, for such is the way of Bnos Yisrael. Kalasah is a basket with a cavity in the bottom to fit on her head.

Hagahos Ashri: In the Chatzer she fulfills Das Yehudis even without Kalasah.

Rif and Rosh (Kesuvos): The Yerushalmi says that a Chatzer through which many people pass is like a Mavoy. A Mavoy through which few people pass is like a Chatzer.

Rambam (12): Das Yehudis is the modest conduct of Bnos Yisrael. One who does any of the following transgresses Das Yehudis. (1) She goes out in the market or an open Mavoy with her head uncovered, without a scarf like all women, even if she wears a kerchief.

Gra (EH 115:10): The Rambam does not mention a Chatzer. He holds that the Gemara requires Kalasah in a half-closed Mavoy between Chatzeros. Therefore, he omits the Yerushalmi that permits a Chatzer or Mavoy through which few people pass.

Rambam (ibid.): (2) She spins in the market with a rose or something similar by her face, on her forehead or cheek, like lewd Nochriyos do. (3) She shows her arms to men while spinning. (4) She jests with Bochurim. (5) She requests Bi'ah with her husband in a loud voice, and the neighbors hear. (6) She curses her husband's father in front of her husband.

Poskim

Shulchan Aruch (EH 115:4): Das Yehudis is the modest conduct of Bnos Yisrael. One who does any of the following transgresses Das Yehudis. (1) She goes out in the market, an open Mavoy or a Chatzer through which many people pass with her head uncovered, without a scarf like all women, even if she wears a kerchief.

Beis Yosef (DH u'Mah she'Chosav v'Davka): The Ran and Rashi connote that her hair may be fully exposed in the Chatzer. The Tur says 'Lo Tetzei', i.e. she is not divorced for this, but it is improper.

Darchei Moshe (4): The Tur agrees. He wrote in Siman 21 that the Isur of uncovered hair is only in the market. He says 'Lo Teztei' so we will infer that it is Tzeni'us that no woman expose her hair, even in her house, like we find regarding Kimchis. For this she merited that Kohanim Gedolim descend from her (Yoma 47a).

Bach (DH u'Mah she'Chosav): The Tur holds like the Rambam. He permits a Mitpachas in the Chatzer l'Chatchilah. To go through a Mavoy to another Chatzer she should wear Kalasah, but this is not Overes Al Das unless her hair was totally exposed.

Beis Shmuel (9): If her hair is uncovered in the market, she transgresses Das Moshe. If it is covered, but not like Bnos Yisrael do, she transgresses Das Yehudis. SMaG learns from the Yerushalmi that even in the Chatzer her hair may not be totally exposed, and Das Yehudis applies. Regarding divorcing without a Kesuvah, we hold like the Bavli that Das Yehudis applies in a Chatzer only if many go through it. Regarding the Isur to uncover her hair, we hold like the Yerushalmi, for perhaps the Bavli agrees.

Shulchan Aruch (ibid.): (2) She spins in the market with a rose or something similar by her face, on her forehead or cheek, like lewd Nochriyos do. (3) She shows her arms to men while spinning (Rema - and does so regularly). (4) She jests with Bochurim.

Beis Yosef (DH v'Chen ha'Medaberes): Why does the Tur say 'one who speaks or one who jests with Bochurim?' The Gemara explains that 'speaking with all men' is jesting with Bochurim! Rather, the text should say 'one who speaks or jests...' The Tur wanted to cite the words of the Gemara.

Chelkas Mechokek (12): She need not jest. The Mishnah says 'she talks with all men', i.e. unnecessary talk to bring them to frivolity. This is especially with single men. The Mishnah discusses Bochurim, for this is a typical case.

Shulchan Aruch (ibid.): (5) She requests Bi'ah with her husband in a loud voice, and the neighbors hear. (6) She curses her husband's father in front of her husband.

Rema: Some say that the same applies if she curses her husband's father in front of her husband's father, or curses her husband in front of her husband.