A piyyut or piyut (plural piyyutim or piyutim, Hebrew פּיּוּטִים / פיוטים, פּיּוּטִ / פיוט ; from Greek ποιητής poiétḗs "poet") is a Jewish liturgical poem, usually designated to be sung, chanted, or recited during religious services. Piyyutim have been written since Temple times. Most piyyutim are in Hebrew or Aramaic, and most follow some poetic scheme, such as an acrostic following the order of the Hebrew alphabet or spelling out the name of the author.
Many piyyutim are familiar to regular attendees of synagogue services. For example, the best-known piyyut may be Adon Olam ("Master of the World"), sometimes (but almost certainly wrongly) attributed to Solomon ibn Gabirol in 11th century Spain. Its poetic form consists of a repeated rhythmic pattern of short-long-long-long, and it is so beloved that it is often sung at the conclusion of many synagogue services, after the ritual nightly saying of the Shema, and during the morning ritual of putting on tefillin. Another well-beloved piyyut is Yigdal ("May God be Hallowed"), which is based upon the Thirteen Principles of Faith developed by Maimonides.
Important scholars of piyyut today include Shulamit Elizur and Joseph Yahalom, both at Hebrew University.
The author of a piyyut is known as a paytan or payyetan (plural paytanim).