| 1. | a coat or jacket worn under another. |
| 2. | Zoology. a growth of short fur or hair lying beneath a longer growth. |
| 3. | an undercoating. |
| 4. | a coat of paint or the like applied under the finishing coat. |
| 5. | a paint, sealer, or the like specially prepared for use underneath a finishing coat. |
| 6. | to apply an undercoating to. |