A coat worn under another; a light coat, as distinguished from an overcoat, or a greatcoat.
- A coat worn beneath another coat.
- A covering of short hairs lying underneath the longer outer hairs of an animal's coat.
- A coat of sealing material applied to a surface before the outer coats, as of paint, are applied.
- The sealing material used for this purpose.
- A tarlike substance sprayed on the underside of a vehicle to prevent rusting.
- To apply an undercoat to.