Delphinid

Part of speech: noun, adjective

Definitions

1. Any of the toothed whales belonging to the family Delphinidae, such as ordinary dolphins, orcas and pilot whales
2. A sea-dwelling mammal from the family Delphinidae that includes common dolphins, killer whales and the larger pilot whales
3. Describing or referring to a member of the oceanic dolphin family, a group of small toothed cetaceans with a prominent beak

Etymology: Delphinid is a technical coinage, not an ancient word, though it is built from a very old Greek root. The Greek "delphis" meant "dolphin" (and in older usage could also mean the womb, a sense probably linked to the animal's shape), and it was the basis for the Latin "delphinus," which gave English "dolphin" by way of Old French. Modern scientists needed a precise term for the whole group rather than the single animal, so they took the Latin stem "delphin-" and added the suffix "-id," used in zoology to mark members of a family. The result, "Delphinidae," names the family of oceanic dolphins, and "delphinid" is the English adjective and noun drawn from it. The suffix is the key to the word's logic: "-id" in biological naming signals a family, so a delphinid is any animal belonging to that family, whether a bottlenose, an orca, or a pilot whale. The "-id" ending sits on a shared stem, which is why the same pattern appears in words like "felid" and "canid."