Source : Webster's Revised Unabridged Dictionary (1913)

Improvisate \Im*prov"i*sate\, a. [See {Improvise}.]
   Unpremeditated; impromptu; extempore. [R.]

Improvisate \Im*prov"i*sate\, v. t. & i. [imp. & p. p.
   {Improvisated}; p. pr. & vb. n. {Improvisating}.]
   To improvise; to extemporize.