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."