thorn

noun

• 1a stiff, sharp-pointed woody projection on the stem or other part of a plant.
• a source of discomfort, annoyance, or difficulty; an irritation or obstacle:the issue has become a thorn in renewing the peace talks

• 2 (also thorn bush or thorn tree) a thorny bush, shrub, or tree, especially a hawthorn.

• 3an Old English and Icelandic runic letter, þ or Þ, representing the dental fricatives /ð/ and /θ/. It was eventually superseded by the digraph th. Compare with eth.

  [so named from the word of which it was the first letter]

• 4a yellowish-brown woodland moth which rests with the wings raised over the back, with twig-like caterpillars.

  • Ennomos and other genera, family Geometridae