Order Isospondyli is a scientific classification for a group of fish species that possess a unique spine structure. There are several synonyms that can be used to refer to this order of fish, depending on the context and purpose of reference. For example, Isospondyli can be used as a common alternative to Order Isospondyli and carries the same meaning. Other synonyms include the term "tailed amphibians" and "archaic fish." These alternative names can be used by researchers, students or enthusiasts for better understanding and ease of reference. Regardless of the name used, Isospondyli fish remain fascinating creatures with unique features that make them stand out from other fish species.