1.AdjectiveRefusing to move or to change one's opinion; obstinate; firmly resisting; persistent in doing something.
"People are pretty stubborn about their political beliefs, so why bother arguing?; Blood can make a very stubborn stain on fabrics if not washed properly."
2.AdjectivePhysically stiff and inflexible; not easily melted or worked.
3.NounStubbornness.
4.NounEllipsis of stubborn disease (“a disease of citrus trees”).