Etymology

Etymology
The name is originally from Greek δελφίς (delphís), “dolphin”,[2] which was related to the Greek δελφύς (delphus), “womb”.[2] The animal’s name can therefore be interpreted as meaning “a ‘fish’ with a womb”.[3] The name was transmitted via the Latin delphinus[4] (the romanization of the later Greek δελφῖνος – delphinos[2]), which in Medieval Latin became dolfinus and in Old French daulphin, which reintroduced the ph into the word “Dolphin”. The term mereswine (that is, “sea pig”) has also historically been used.[5]

The term ‘dolphin’ can be used to refer to, under the parvorder Odontoceti, all the species in the family Delphinidae (oceanic dolphins) and the river dolphin families Iniidae (South American river dolphins), Pontoporiidae (La Plata dolphin), Lipotidae (Yangtze river dolphin) and Platanistidae (Ganges river dolphin and Indus river dolphin).[6][7] This term has often been misused in the US, mainly in the fishi

ng industry, where all small cetaceans (dolphins and porpoises) are considered porpoises,[8] while the fish dorado is called dolphin fish.[9] In common usage the term ‘whale’ is used only for the larger cetacean species,[10] while the smaller ones with a beaked or longer nose are considered ‘dolphins’.[11] The name ‘dolphin’ is used casually as a synonym for bottlenose dolphin, the most common and familiar species of dolphin.[12] There are six species of dolphins commonly thought of as whales, collectively known as blackfish:

the killer whale, the melon-headed whale, the pygmy killer whale, the false killer whale, and the two species of pilot whales, all of which are classified under the family Delphinidae and qualify as dolphins.[13] Though the terms ‘dolphin’ and ‘porpoise’ are sometimes used interchangeably, porpoises are not considered dolphins and have different physical features such as a shorter beak and spade-shaped teeth; they also differ in their behavior. Porpoises belong to the family Phocoenidae and share a common ancestry with the Delphinidae.[12]

A group of dolphins is called a “school” or a “pod”. Male dolphins are called “bulls”, females called “cows” and young dolphins are called “calves”.[14]