Which word describes an event that occurs occasionally and without a clear pattern?

The term that describes an event occurring occasionally and without a clear pattern is "sporadic." This word is used to indicate that something happens irregularly or at intervals, rather than in a steady or predictable manner. For example, one might refer to sporadic rain showers throughout a season, which can occur at various times without any forecastable schedule.

In contrast, "consistent" refers to something that happens regularly and reliably, showing a pattern. "Systematic" suggests a methodical or organized approach, implying order and design in occurrences. "Continuous" indicates that something is ongoing without interruption. These definitions highlight how the characteristics of events differ from those described as sporadic, making "sporadic" the most fitting choice for the scenario presented.