- Delphinus - a constellation in the northern hemisphere near Pegasus and Aquila
--1 is a kind of constellation
- Delphinus, genus Delphinus - type genus of the Delphinidae
--2 is a kind of mammal genus
--2 is a member of Delphinidae, family Delphinidae
--2 has members: common dolphin, Delphinus delphis - Delphinus, genus Delphinus - type genus of the Delphinidae