A chumra (Hebrew: חומרה; pl. חומרות chumrot; alternative transliteration: khumra) is a prohibition or obligation in Jewish practice that exceeds the bare requirements of Halakha (Jewish law). One who imposes a chumra on oneself in a given instance is said to be machmir (מחמיר).
An obligation or prohibition can be adopted by an individual or an entire community. Early references to chumrot are found in the Talmud, and the understanding and application of them has changed over time.
After a chumra has been observed for generations, it can become a minhag, or accepted tradition, and become a binding requirement for individuals from families or communities that adopted the chumra.