The distant origins of the trombone are probably in the whelk, kind of tuba played by the Romans that was a variation in the shape of "S" recalling that of the current trombone - the term whelk was also included in the 19th century to refer to a military orchestra trombone which pavilion was a snake head.
It is probably in the 13th century that came the idea of adding two tubes sliding one on another on a low trumpet. The resulting instrument is called the sacqueboute ("sacquer" meaning pull and "bouter" push towards the opposite direction). This was not a radically different instrument from the trombone, but a slightly smaller version.
In the 17th century, the Italian name of trombone was gradually used to describe the instrument. The origin of the word comes from tromba meaning trumpet and one, a suffix meaning large. Thus, literally, a trombone is a great trumpet.
During its entire history, the trombone, due to its simple principle, has undergone few modifications, mainly of size and shape. Most notable are the appearance of the valve trombone at the beginning of the 19th century in which the slide is replaced by 3 valves in 1814 by Heinrich Stölzel and the addition of the valve patented in 1839 by the German Christian Friedrich Sattler.