The term Class Oligochaeta refers to a group of annelid worms that includes the popular earthworm species. When it comes to synonyms for this term, there are a few options that are commonly used. One such synonym is the term "terrestrial oligochaetes," which highlights the fact that these worms are primarily found on land. Another option is the term "tubificids," which is a reference to a family of Oligochaeta species that are characterized by their funnel-like structures. Additionally, some experts may use the term "lumbricids," which is a reference to the family that includes the common earthworm. Overall, while there are several synonyms for Class Oligochaeta, each term accurately describes a different aspect of this diverse group of worms.