thorn thorn /ˈθɔrn/

noun

1. () Something that causes irritation and annoyance  ( irritant , thorn )
   something that causes irritation and annoyance
    He's a thorn in my flesh
   he's a thorn in my flesh
   
2. A Germanic character of runic origin  ( thorn )
   a Germanic character of runic origin
   
3. A small sharp-pointed tip resembling a spike on a stem or leaf  ( pricker , prickle , spikelet , spine , sticker , thorn )
   a small sharp-pointed tip resembling a spike on a stem or leaf