The sackbut, which dates from the Renaissance, was an early version of which modern musical instrument?

A sackbut is a type of trombone from the Renaissance and Baroque eras, characterised by a telescopic slide that is used to vary the length of the tube to change pitch. Unlike the earlier slide trumpet from which it evolved, the sackbut possesses a U-shaped slide, with two parallel sliding tubes, which allows for playing scales in a lower range.

Records of the term "trombone" predates the term "sackbut" by two decades, and evidence for the German term "Posaune" is even older. "Sackbut", originally a French term, was used in England until the instrument fell into disuse in the 1700s; when it returned, the Italian term "trombone" became dominant. In modern English, an older trombone or its replica is called a sackbut.