Frequent.
The opposite of occasional is frequent.
It could be, if occasional is used to mean as an amateur in a profession. The opposite of occasional would be frequent. Other opposites for career could be avocation or hobby.
Some words have no perfect antonyms. "Occasional" is on a scale: Always...frequently...often...occasionally...seldom...infrequently...rarely...never. There is really no opposite. For words like this, the logical answer is to add "Not". "Not occasional" is the opposite of occasional.
Changeable, occasional
Irregular. Or perhaps... Occasional.
An Occasional Dream was created in 1969.
Occasional Oratorio was created in 1746.
An Occasional Hell was created in 1993.
Occasional Wife - 1966 My Occasional Brother's Keeper 1-27 was released on: USA: 11 April 1967
The duration of Occasional Wife is 1440.0 seconds.
An Occasional Hell has 256 pages.
Grandma's health is very good except for an occasional case of heartburn. Her term papers are usually perfect with the exception of an occasional spelling error. The weather report says to expect occasional showers today. He takes Tylenol PM for occasional sleeplessness.