Definition of "boner"

boner

/ˈbəʊ.nə(ɹ)/

noun
plural boners
1. (vulgar, slang) An erect penis.
  Quotations
  Boys often refer to their enlarged penis as an "erection," a "boner," or a "hard on."
  1973, Sol Gordon, Facts about sex for today's youth‎, page 20
  1. (vulgar, slang, figurative) An often perverse sense of enjoyment from or predilection towards something.
2. One who or that which removes bones.
3. (dated slang, especially baseball) A blunder; a silly mistake.