English Reference
noun

thorn

n.
US /ˈθɔɹn/ UK /θˈɔːn/ thorn UK spelling thorn's, thorn's, thorning

  1. 01 B2 Upper Intermediate Science

    a sharp, pointed part that grows on the stem of a plant, like a rose.

    a sharp-pointed woody projection on the stem or leaf of a plant, technically a modified branch or leaf.

    Simple

    Be careful when you pick the roses because they have sharp thorns.

    In context

    The desert shrubs have evolved long thorns to protect their water-rich stems from hungry animals.

    spinepricklespike
  2. 02 B2 Upper Intermediate

    a person or thing that causes constant problems or annoyance.

    a persistent source of irritation, annoyance, or difficulty; frequently used in the idiom 'a thorn in one's side'.

    Simple

    The new tax law has been a thorn in the side of small business owners.

    In context

    The investigative journalist remained a constant thorn in the administration's side, regularly exposing corruption in the local government.

  3. 03 C2 Proficiency Technical

    an old letter used in English long ago, and still used in Icelandic, to make the 'th' sound.

    a character (Þ, þ) used in Old English and modern Icelandic to represent dental fricatives.

    Simple

    In Old English manuscripts, you will often see the letter thorn instead of 'th'.

    In context

    Linguists note that the letter thorn was eventually replaced by the 'th' digraph in Middle English due to the influence of continental scribes.

You gotta get past the thorns to get to the beautiful rose.

The Guardian· 3 Sept 2026
This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated