Extemporaneous

Ex*tem`po*ra"ne*ous (?), a. [See Extempore.] Composed, performed, or uttered on the spur of the moment, or without previous study; unpremeditated; off-hand; extempore; extemporary; as, an extemporaneous address or production. -- Ex*tem`po*ra"ne*ous*ly, adv. -- Ex*tem`po*ra"ne*ous*ness,n.