dytiscidPronunciation: /dɪˈtɪskɪd, -sɪd/Definition of dytiscid noun Entomology a beetle of a family (Dytiscidae) that comprises most water beetles. Origin: mid 19th century: from modern Latin Dytiscidae, from Dytiscus (genus name), from Greek dutikos 'able to dive', from duein 'dive'