1. Limited in duration to a single episode
   "an account concerned primarily with episodical events such as the succession of rulers";
   - episodic
    
2. Occurring or appearing at usually irregular intervals
   "episodical in his affections";
   - episodic, occasional
    
3. Of writing or narration; divided into or composed of episodes
   "the book is episodical and the incidents don't always hang together";
   - episodic

See also: divided, impermanent, temporary, unpredictable