water beetle
NounWordNet 3.0
Noun (1)
- any of numerous aquatic beetles usually having a smooth oval body and flattened hind legs for swimming
Webster's Dictionary (GCIDE)
Water beetle \Wa"ter bee"tle\ (Zool.) Any one of numerous species of aquatic beetles belonging to Dytiscus and allied genera of the family Dytiscidae, and to various genera of the family Hydrophilidae. These beetles swim with great agility, the fringed hind legs acting together like oars. [1913 Webster]