Which term describes something that occurs in scattered and irregular or unpredictable instances?

The term that describes something occurring in scattered and irregular or unpredictable instances is "sporadic." This word is derived from the Greek word "sporadikos," meaning "scattered," and it signifies occurrences that do not happen consistently or regularly. In various contexts, such as weather patterns, health events, or even attendance at an event, "sporadic" effectively communicates the idea of infrequent and erratic manifestations.

For instance, one might refer to sporadic rain showers that are unpredictable and happen at irregular intervals throughout the day. The essence of the term captures the unpredictability and lack of a steady pattern in the occurrences described.