Flatworm/ˈflætwɜːrm/ Definition 1 of 1Pro Tip 1/3Biology Context Flatworms are studied in biology; they're not mentioned in daily conversation. In biology class, we examined a flatworm under the microscope. Pro Tip 2/3Not Always Parasitic While some flatworms are parasites, many are harmless, so don't assume they're all dangerous. Not every flatworm poses a threat to other animals. Pro Tip 3/3Regeneration Interest Flatworms are known for regenerative abilities, sparking scientific interest. Scientists study flatworms to learn about regrowing lost body parts.