ETYM as. thorn; akin to os. and OFries. thorn, Dutch doorn, German dorn, Dan. torn, Swed. törne, Icel. thorn, Goth. thaúrnus; cf. Pol. tarn, Russ. tern the blackthorn, ternie thorns, Skr. torna grass, blade of grass.
1. A woody plant bearing sharp impeding processes (as prickles or spines); especially; hawthorn.
2. A sharp rigid process on a plant; specifically; a short, indurated, sharp-pointed, and leafless modified branch; any of various sharp spinose structures on an animal.
3. The runic letter X used in Old English and Middle English to represent either of the fricatives and in Icelandic to represent.
4. Something that causes distress or irritation — often used in the phrase thorn in one's side.
5. A Germanic character of runic origin.