The Collaborative International Dictionary of English v.0.48:

Cadenza \Ca*den"za\, n. [It.] (Mus.)
   A parenthetic flourish or flight of ornament in the course of
   a piece, commonly just before the final cadence.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cadenza
    n 1: a brilliant solo passage occurring near the end of a piece
         of music

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "cadenza":
   acciaccatura, appoggiatura, arabesque, cadence, coloratura,
   division, embellishment, extempore, fioritura, flight, flourish,
   grace, grace note, hot lick, impromptu, improvisation, incidental,
   incidental note, interpolation, lick, long mordent, mordent,
   ornament, passage, pralltriller, riff, roulade, run,
   single mordent, turn, vamp