what is a dero
Definition of DERO. : a genus of small aquatic oligochaete worms (family Naididae) having an expanded anal hood from which project two pairs of cylindrical ciliated gills. ADVERTISEMENT.ote that some information is displayed differently in the Unabridged. To access the complete Unabridged Dictionary, with an additional 300,000 words that aren't in our free dictionary, start a free trial.