[thorn] n, often attrib [ME, fr. OE; akin to OHG dorn thorn, Skt trna grass, blade of grass] (bef. 12c) 1: a woody plant bearing sharp impeding processes (as briers, prickles, or spines); esp: hawthorn
2. a: a sharp rigid process on a plant; specif: a short, indurated, sharp-pointed, and leafless modified branch b: any of various sharp spinose structures on an animal
3: the runic letter used in Old English, Middle English, and Icelandic to represent the /th/ fricatives
4: something that causes distress or irritation--often used in the phrase thorn in one's side -- thorned adj -- thorn.less adj -- thorn.like adj