Source : Webster's Revised Unabridged Dictionary (1913)
Thorn \Thorn\, n. [AS. [thorn]orn; akin to OS. & OFries. thorn,
D. doorn, G. dorn, Dan. torn, Sw. t["o]rne, Icel. [thorn]orn,
Goth. [thorn]a['u]rnus; cf. Pol. tarn, Russ. tern' the
blackthorn, ternie thorns, Skr. t[.r][.n]a grass, blade of
grass. [root]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 Crat[ae]gus, 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}. (Zo["o]l.) See {Moloch}, 2.
{Thorn hopper} (Zo["o]l.), a tree hopper ({Thelia
crat[ae]gi}) which lives on the thorn bush, apple tree,
and allied trees.
Source : WordNet®
thorn apple
n : any of several plants of the genus Datura