The term PLAYFUL RIVER ANIMAL is referring to an otter, which is a five-letter word. Otters are semi-aquatic mammals that live in rivers, streams, and coastal areas. They are known for their playful behavior and are often seen sliding down muddy banks or playing with rocks and sticks. Otters have webbed feet and a thick fur coat that helps them stay warm and dry in the water. They are also very social animals and can be found in groups of up to 15 individuals.