1. The act or practice of observing or complying with a law, custom, command, or rule.

2. The act or custom of keeping or celebrating a holiday or other ritual occasion.

3. A customary rite or ceremony.

4. The act of watching; observation: "Consider how much intellect was needed in the architect, and how much observance of nature" (John Ruskin).

5. Roman Catholic Church The rule governing a religious order.