Learner's definition of OCCASIONAL
always used before a noun
1 : happening or done sometimes but not often : not happening or done in a regular or frequent way
She receives occasional phone calls from her mother.
There will be occasional showers during the morning.
She makes occasional appearances on television. = She appears on the occasional television show.
Most mornings, we'll see deer or the occasional bear walking past our house.
He tells an occasional joke to keep his students interested.
I need to take occasional breaks from work.
Sure, I drink an occasional glass of wine from time to time.
2 : sometimes doing a particular job or activity