dolphin
n. countable A2 Elementary US //ˈdɑɫfən// UK //dˈɒlfɪn// dol·phin
n. a smart sea animal that looks like a large fish but breathes air. They are famous for being friendly to people and jumping out of the water.
n. a highly intelligent aquatic mammal belonging to the infraorder Cetacea, characterised by a streamlined body and a snout shaped like a beak.
We saw a dolphin jumping near our boat today.
The researchers spent the afternoon tracking a pod of dolphins as they moved along the coast.
Marine biologists have long studied the sophisticated sonar systems and social structures that allow dolphins to coordinate complex hunting strategies in the open ocean.
Usage
The plural form is typically 'dolphins'; 'dolphin' is occasionally used as a collective plural in a nautical or fishing context.