How can "systematic" be defined?

"Systematic" refers to something that is methodical and organized, following a planned and structured approach. The word conveys the idea of consistency and order in processes or actions. When something is described as systematic, it implies that it occurs in a regular pattern or through a coherent system, making it reliable and predictable.

In the context of the given choices, the term "regular" aligns with the definition of "systematic," as both suggest a sense of organization and a non-arbitrary method to how actions or processes are carried out. Regularity implies repeated occurrence in a predictable manner, which is a core aspect of systematic processes.

While the other options convey notions of randomness or lack of organization—such as irregularity, haphazardness, and randomness—they differ significantly from the systematic approach, which is characterized by order and method. Recognizing this difference in meaning illustrates why "regular" is the suitable definition for "systematic."