Definition of thorn

• n. - A hard and sharp-pointed projection from a woody stem; usually, a branch so transformed; a spine.
• n. - Any shrub or small tree which bears thorns; especially, any species of the genus Crataegus, as the hawthorn, whitethorn, cockspur thorn.
• n. - Fig.: That which pricks or annoys as a thorn; anything troublesome; trouble; care.
• n. - The name of the Anglo-Saxon letter /, capital form /. It was used to represent both of the sounds of English th, as in thin, then. So called because it was the initial letter of thorn, a spine.
• v. t. - To prick, as with a thorn.