underfur vs undercoat

underfur and undercoat both are nouns.

Word	Noun	Adjective	Verb	Adverb
underfur	Yes	No	No	No
undercoat	Yes	No	Yes	No

As nouns, underfur and undercoat are synonyms defined as:

underfur and undercoat: thick soft fur lying beneath the longer and coarser guard hair

underfur (noun)	undercoat (noun)
thick soft fur lying beneath the longer and coarser guard hair	thick soft fur lying beneath the longer and coarser guard hair
	the first or preliminary coat of paint or size applied to a surface
	seal consisting of a coating of a tar or rubberlike material on the underside of a motor vehicle to retard corrosion

underfur (verb)	undercoat (verb)
	cover with a primer; apply a primer to