I found the word in dictionary but that's not it. I need it fast, if you know hurry up, and I'll give 10 to first!
Answers:
The noun "flank", and using "flank" as a verb, are military terms:
"Flank - (n) also called a wing; either end of a mobile or fortified military position; a refused flank is attached to or protected by terrain, a body of water, or defended fortifications, while one that is not protected is said to be "in the air"; (v) a maneuver that seeks to avoid a frontal assault by gaining the side or read of an enemy postition."