a small sharp, pointed part on the stem of some plants, such as roses （玫瑰之类植物的）刺，棘刺 
a tree or bush that has thorns 带刺的树；荆棘 the letter that was used in Old English and Icelandic to represent the sounds /θ/ and /ð/ and later written as th 刺形符，字母 ð（古英语和古冰岛语用的字母，表示 /θ/ 和/ð/ 的发音，后书写为 th）
Word OriginOld English, of Germanic origin; related to Dutch doorn and German Dorn.
Idioms
a thorn in somebody’s flesh/side
a person or thing that repeatedly annoys somebody or stops them from doing something 不断让人烦心的人（或事）；肉中刺；眼中钉