Lavash (Armenian: լավաշ; Persian: لواش, romanized: lavâš) is a thin flatbread usually leavened, traditionally baked in a tandoor (tonir or tanoor) or on a sajj, and common to the cuisines of South Caucasus, West Asia, and the areas surrounding the Caspian Sea. Lavash is widespread in Armenia.

In 2014, "Lavash, the preparation, meaning and appearance of traditional bread as an expression of culture in Armenia" was inscribed in the UNESCO Representative List of the Intangible Cultural Heritage of Humanity. In 2016, the making and sharing of flatbread (lavash, katyrma, jupka or yufka) in communities of Azerbaijan, Iran, Kazakhstan, Kyrgyzstan, and Turkey was inscribed on the list as well. Lavash is similar to yufka, but in Turkish cuisine lavash (lavaş) is prepared with a yeast dough while yufka is typically unleavened.

The word lavash entered English partly from Armenian (լավաշ, lavaš), Persian (لواش, lavaš), and Turkish (lavaş). Similar names are used in many Asian languages, including Georgian (lavaš-i), Azerbaijani (lavaš), Tatar (lawaš), Turkmen (lavaš), and Pashto (lawausha). Lavash is the most common name for the bread in American English; the spellings lavosh, lahvosh, lawaash, and lawasha are also used. Other English terms include cracker bread, Armenian cracker bread, mountain bread, and paraki. The Arabic equivalent is called khobiz sajj, or markouk in Lebanon.

The etymology of lavash is unknown. A widely held theory states that the word spread to other languages from Persian. Sevan Nişanyan connects the Persian word for lavash to the Aramaic לושׁ lwš root meaning 'to knead' and recorded al-Faraj ba'd ash-Shiddah from 1451 as the oldest text to use the term in Turkish. Hrach Martirosyan tentatively connects the Armenian word with words derived from Proto-Armenian *law 'flat'. One theory states that the Azeri word is derived from a Turkic root, ash, meaning 'to cook'. The word lavash is attested in the first dictionary of the Turkic languages, the Dīwān Lughāt al-Turk (1072–1074).

Lavash is made with wheat flour kneaded with water and salt, forming a stiff dough. High-extraction flour is typically used, at about 80–82% extraction. Leavened and unleavened forms of lavash exist. It may be leavened with yeast or with a sourdough starter known in Armenian as ttkhmor, which consists of dough from the previous batch. Some producers in Iran instead use baking soda, although this is prohibited by the Ministry of Health. A mixture of yeast and baking soda may also be used. The dough of lavash and the similar sangak contain about 83% flour by weight, higher than other breads in Iran. For every 100 g flour, lavash dough may have about 45–55 g water, 2 g salt, 1 g least, and 0.25 g baking soda.

The leavened dough may be fermented for 30–60 minutes, at about 30°C, before being shaped into 100–300 gram balls, then risen again for 5–20 minutes. The dough is rolled with a rolling pin, commonly a thin rod known as an okhlavoo. Then, it may be rolled with a spiked rolling pin that forms indentations.

The dough is slapped against the hot walls of a tandoor (also known as tonir or tanoor), a type of clay oven. To place the dough in the oven, it is stretched over a round cushion with a handle, functioning as a peel. This tool is known in Iran as saruj and in Armenia as batat or rabata. Lavash cooks very quickly—about 15 to 40 seconds—due to thermal radiation and convection from the flame and conduction from the wall. The bread is removed using a metal hook and stacked. Aside from a tandoor, lavash may be baked on top of a saj, a metal pan. This may be placed in or on a wood-powered oven, or over an open fire. In the modern era, electric ovens are commonly used.

Being cooked on the side of a tandoor causes irregular coloring in lavash, comparable to naan. It bubbles and browns while cooking, and the final product is cream-colored with spots across the surface. The colour of machine-produced lavash is more regular. Lavash is pliable and strong enough to hold other foods.