Main entry: periodic, occasional
Definition: recurring or reappearing from time to time
Usage: periodic feelings of anxiety
Main entry: occasional
Definition: occurring from time to time
Usage: took an occasional glass of wine
Main entry: episodic, occasional
Definition: occurring or appearing at usually irregular intervals
Usage: episodic in his affections; occasional headaches
Main entry: occasional, casual
Definition: occurring from time to time
Usage: casual employment; a casual correspondence with a former teacher; an occasional worker