Trombone. Or, since you specified bass a bass trombone.
A bigger trombone is usually a bass trombone.
Obviously the smaller tenor trombone would have room to spare inside a bass bag.
The bass trombone is typically played in the key of Bb.
Tenor and bass, but there is sometimes an alto trombone too. In a section of three trombones, there will either be one of each, or two tenors and one bass.
A baritone horn looks somewhat like a miniaturized tuba. A bass trombone is still a trombone, but slightly larger. It also has an F trigger, which opens up more tubing near the bell of the trombone and changes the note. This allows players to reach the range from a low E flat to a low B, which is physically impossible on a tenor trombone. Some bass trombones also include another trigger, G flat, which can be opened separately or in combination with the F trigger.
Bass
The trombone mouthpiece is exactly the same as an euphonium one. You may also (with difficulty) manage to play a Bass Trombone or Tuba with a tenor trombone mute
Bass trombone
The Trombone does NOT transpose, the player does. With that said, if the music is written in Bb Bass Clef, one does transpose in Bass clef. Most Bass Clef music is in C Bass clef, but the player has learned how to read in concert pitch, so there is no transposition needed.
Yes, tromba is latin for trumpet and one is latin for big. So trombone means big trumpet
The most common instrumentation is two trumpets or cornets one horn, one trombone or euphonium /baritone horn, and one tuba or bass trombone