blindside vs flank

blindside

verb
  • To attack (a person) on his or her blind side. 

  • To catch off guard; to take by surprise. 

noun
  • The blindside flanker, a position in rugby union, usually number 6. 

  • A person's weak point. 

  • A tram/train driver's field of blindness around a tram (trolley/streetcar) or a train; the side areas behind the tram/train driver. 

  • The space on the side of the pitch with the shorter distance between the breakdown/set piece and the touchline; compare openside. 

  • A driver's field of blindness around an automobile; the side areas behind the driver. 

flank

verb
  • To attack the flank(s) of. 

  • To be placed to the side(s) of something (usually in terms of two objects, one on each side). 

  • To defend the flank(s) of. 

  • To place to the side(s) of. 

adj
  • Maximum. Historically faster than full speed (the most a vessel can sustain without excessive engine wear or risk of damage), now frequently used interchangeably. Typically used in an emergency or during an attack. 

noun
  • The flesh between the last rib and the hip; the side. 

  • The sides of a bastion perpendicular to the wall from which the bastion projects. 

  • The outermost strip of a road. 

  • The wing, one side of the pitch. 

  • That part of the acting surface of a gear wheel tooth that lies within the pitch line. 

  • A cut of meat from the flank of an animal. 

  • The side of something, in general senses. 

  • The extreme left or right edge of a military formation, army etc. 

How often have the words blindside and flank occurred in a corpus of books? (source: Google Ngram Viewer )