The term 'Big Brass Instrument' can be summarized as a TUBA, which is a four-letter word. The TUBA is a large, conical-bore, brass instrument that is the lowest-pitched instrument in the brass family. It is most commonly used in orchestras, concert bands, and marching bands. It is also used in jazz, solo, and chamber music. The TUBA is known for its deep, rich sound and is often used to provide a strong bass line in ensembles.