What does "improvise" mean?

Improvise: To bring about, arrange, or make, on a sudden, or without previous preparation. Charles attempted to improvise a peace. Motley.

Additional senses

  1. 2.To invent, or provide, offhand, or on the spur of the moment; as, he improvised a hammer out of a stone.
  2. 3.To produce or render extemporaneous compositions, especially in verse or in music, without previous preparation; hence, to do anything offhand.

Sources