The third-stage larva of a parasitic fluke. Rediae develop within the body of a freshwater snail and undergo a process of asexual reproduction, giving rise to many fourth-stage larvae called cercariae.
The stage in the life cycle of a trematode that follows the sporocyst stage. It is a saclike form with an oral sucker and a blind gut. Rediae are produced within the sporocyst and in turn develop into second-generation rediae or cercariae.