Thayer's Greek Lexicon

 1. a sting, as that of bees, scorpions, locusts. Since animals
wound by their sting and even cause death, Paul attributes
death, personified as a sting, i.e. a deadly weapon
2. an iron goad, for urging on oxen, horses and other beasts of burden
  1) hence the proverb, "to kick against the goad", i.e. to offer
vain and perilous or ruinous resistance