1. The act of moving round, or in a circle, or in a course which brings or tends to bring the moving body to the point where its motion began; as the circulation of the blood in the body.
2. A series in which the same order is preserved and things return to the same state.
3. The act of going and returning; or of passing from place to place, or from person to person; as the circulation of money.
4. Currency; circulating coin, or notes or bills current for coin.
5. In chimistry, circulation is an operation by which the same vapor, raised by fire, falls back to be returned and distilled several times.