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The term tzniut (Hebrew: ‎, tzniut, Sephardi pronunciation, tzeniut(h); Ashkenazi pronunciation, tznius, "modesty", or "privacy") is used within Judaism, and has its greatest influence as a concept within Orthodox Judaism. It is used to describe both the character trait of modesty and humility, as well as a group of Jewish laws pertaining to conduct in general, and especially between the sexes. The term is frequently used with regard to the rules of dress for women.

Humility is a paramount ideal within Judaism. Moses is referred to as "exceedingly humble, more than any man in the world" (Book of Numbers 12:3), though the adjective used of Moses is anav (ענו), and not tzana (צָנַע), the cognate of the noun tzniut. The verb tzana "to be humble" occurs in Proverbs 11:2 and, (in the hiphil), "walk humbly" in Micah 6:8.

The Talmud states that humility is one of the characteristic traits of the Jewish people (Talmud, Tractate Yevamot 79a).

Tzniut includes a group of laws concerned with modesty, in both dress and behavior. In the Babylonian Talmud, Rabbi Elazar Bar Tzadok connected the injunction at Micah 6:8 to "walk humbly with your God" as referring to modesty and discretion in dress and in behavior (Tractate Sukkah 49b).

In the legal dimension of Orthodox Judaism, the issue of tzniut is discussed in more technical terms: how much skin may a person expose, and so on. Notwithstanding these details, the concept of humility and modesty as a positive character trait, a practice, and a way of life—a "way of walking"—is also taught to be important in Rabbinic literature. This awareness informs the concept and the practice of tzniut in its rules and details.

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