Thorn (?), n. [AS. þorn; akin to OS. & OFries. thorn, D. doorn, G. dorn, Dan. torn, Sw. törne, Icel. þorn, Goth. þaúrnus; cf. Pol. tarn, Russ. tern' the blackthorn, ternie thorns, Skr. tṛṇa grass, blade of grass. √53.] 1. A hard and sharp-pointed projection from a woody stem; usually, a branch so transformed; a spine.
2. (Bot.) Any shrub or small tree which bears thorns; especially, any species of the genus Cratægus, as the hawthorn, whitethorn, cockspur thorn.
3. Fig.: That which pricks or annoys as a thorn; anything troublesome; trouble; care.
There was given to me a thorn in the flesh, the messenger of Satan to buffet me. 2 Cor. xii. 7.
The guilt of empire, all its thorns and cares,
Be only mine. Southern.
4. 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.
Thorn apple(Bot.), Jamestown weed. — Thorn broom(Bot.), a shrub that produces thorns. — Thorn hedge, a hedge of thorn-bearing trees or bushes. — Thorn devil. (Zoöl.) See Moloch, 2. — Thorn hopper(Zoöl.), a tree hopper (Thelia cratægi) which lives on the thorn bush, apple tree, and allied trees.