What does the word fin mean?

Usage examples for fin

  1. He pointed to a huge shark, its triangular fin just above the surface, keeping two or three fathoms off, even with the boat, at which the monster every now and then, as he declared, gave a wicked leer. – The Three Lieutenants by W.H.G. Kingston
  2. If you are so careless, you will soon not have a whole fin to your back- or your front either. – Among the Pond People by Clara Dillingham Pierson