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1.
A medieval rock-hard trombone
Yo! Stop playin the sackbut so loud!!!!
by Ihatesu April 26, 2006
 
2.
A brass instrument from the Renaissance and Baroque Eras; an the ancestor of the modern trombone.

Sackbuts (renaissance/baroque trombones) are often described as being generally quieter, having a more mellow tone and wider pallette of articulations than the modern trombone.
A sackbut is a musical instrument that resembles a trombone.
by tcufrog08 March 31, 2008