![underfur underfur](https://www.tekportal.net/wp-content/uploads/2018/11/underfur.jpg)
noun
- the fine, soft, thick, hairy coat under the longer and coarser outer hair in certain animals, as seals, otters, and beavers.
noun
- the layer of dense soft fur occurring beneath the outer coarser fur in certain mammals, such as the otter and sealAlso called: undercoat