Definitions of flank:

• noun:   the side between ribs and hipbone
• noun:   a cut from the fleshy part of an animal's side between the ribs and the leg
• noun:   the side of military or naval formation

  Example: "They attacked the enemy's right flank"

• noun:   a subfigure consisting of a side of something
• verb:   be located at the sides of something or somebody
• name:  A surname (very rare: popularity rank in the U.S.: #47427)