occasional

Occurring or appearing irregularly from time to time, but not often; incidental.

• He was mostly solitary, but enjoyed the occasional visitor.
• He took an occasional glass of wine.

Created for a specific occasion.

• Elgar's music was not created to be occasional music for high-school graduations.

Intended for use as the occasion requires.

• What your living room needs are some occasional chairs.

Acting in the indicated role from time to time.

• He is an occasional writer of letters to the editor.

A person who does something only occasionally.