Cadenza

From Conservapedia

A Cadenza is a parenthetic flourish in a solo piece commonly just before a final or other important cadence. In a concerto, a cadenza will often have the orchestra stop playing while the soloist performs alone. While cadenzas were originally improvised, modern music typically writes out the cadenza portion.

Notable Cadenzas

Beethoven's "Emporor" Concerto

Aaron Copland's Clarinet Concerto

Tartini's "Devil's Trill" Sonata