Improvisation
Pronunciation : Im*prov`i*sa"tion
Part of Speech : n.
Etymology : [Cf. F. improvisation.]
Definition : 1. The act or art of composing and rendering music, poetry, and the like, extemporaneously; as, improvisation on the organ.
2. That which is improvised; an impromptu.
Source : Webster's Unabridged Dictionary, 1913