thorn
n. countable B2 Upper Intermediate US //ˈθɔɹn// UK //θˈɔːn// thorn
n. a sharp, pointed part on the stem of a plant like a rose. It protects the plant by making it painful for animals to touch or eat it.
n. a sharp-pointed woody projection on the stem or another part of a plant. Often used metaphorically to describe a persistent source of irritation or trouble.
I pricked my finger on a sharp thorn while picking roses.
The thick bushes were covered in long thorns, making it impossible for us to walk through the garden.
The poet used the image of a single thorn to represent the hidden pain within an otherwise beautiful relationship.
Usage
Commonly appears in the idiom 'a thorn in someone's side' to describe a constant annoyance.