Occasional (adjective)

1. Happening or done only occasionally; not regular or constant.
2. Providing or suitable for a special occasion.

Origin:

Middle english, from old french occasionnel, from latin occasionalis, from occasion- (stem of occasio) opportunity.

Examples:

1. I have an occasional glass of wine.
2. He was an occasional visitor to the city.
3. We have occasional meetings to discuss progress.
4. She was an occasional actress.
5. This is an occasional table.