1. (v. t.) To compose, recite, or sing extemporaneously, especially in verse; to extemporize; also, to play upon an instrument, or to act, extemporaneously.

2. (v. t.) To bring about, arrange, or make, on a sudden, or without previous preparation.

3. (v. t.) To invent, or provide, offhand, or on the spur of the moment; as, he improvised a hammer out of a stone.

4. (v. i.) To produce or render extemporaneous compositions, especially in verse or in music, without previous preparation; hence, to do anything offhand.