a Germanic character of runic origin Þ used in Old and Modern Icelandic to represent the voiceless dental fricative sound of th, as in thin, bath. Its use in phonetics for the same purpose is now obsoleteSee theta
this same character as used in Old and Middle English as an alternative to edh, but indistinguishable from it in function or soundCompare edh
zoologyany of various sharp spiny parts
a source of irritation (esp in the phrases a thorn in one's sideorflesh)
Derived Formsthornless, adjective
Word Origin for thorn
Old English; related to Old High German dorn, Old Norse thorn
Old English þorn "sharp point on a stem or branch," earlier "thorny tree or plant," from Proto-Germanic *thurnuz (cf. Old Saxon thorn, Dutch doorn, Old High German dorn, German Dorn, Old Norse þorn, Gothic þaurnus), from PIE *trnus (cf. Old Church Slavonic trunu "thorn," Sanskrit trnam "blade of grass," Greek ternax "stalk of the cactus," Irish trainin "blade of grass"), from *(s)ter-n- "thorny plant," from root *ster- "stiff."
Figurative sense of "anything which causes pain" is recorded from early 13c. (thorn in the flesh is from II Cor. xii:7). Also an Anglo-Saxon and Icelandic runic letter (þ), named for the word of which it was the initial.
Also, thorn in one's side. A constant source of irritation, as in Paul's complaining and whining are a thorn in my flesh, or Mother's always comparing us children—it's a thorn in our sides. This metaphoric expression appears twice in the Bible. In Judges 2:3 it is enemies that “shall be as thorns in your sides”; in II Corinthians 12:7 Paul says his infirmities are “given to me a thorn in the flesh.”