If you have an episodic interest in professional sports, you pay attention to sports from time to time, but you're not a regular fan. The adjective episodic is often used to mean "occasional" or "every once in a while."
If you have a bad cough that comes and goes, you could call it an "episodic condition." When used in this way, episodic suggests that the cough appears at irregular, or random, intervals. Episodic can also describe the way certain stories are told. An "episodic narrative" is a story that is told through a series of episodes, or segments. A soap opera on television, for instance, is an episodic program.