noun
giant otter; giant river otter
Refers specifically to the species Pteronura brasiliensis, a large South American otter.
オオカワウソは南米の川に生息している。
Giant otters inhabit rivers in South America.
動物園でオオカワウソの群れを見
I saw a group of giant otters at the zoo.
カワウソ is the general term for 'otter'; オオカワウソ specifies the giant otter species.
Compound of 大 (おお, 'big') and カワウソ (かわうそ, 'otter'). The exact origin of カワウソ is uncertain, but it is a native Japanese word.