arris vs flank

arris

noun
  • A sharp edge or ridge formed by the intersection of two surfaces 

  • A ridge formed on the surface of flaked stone, such as a arrowhead or hand axe, as the result of the intersection of two or more flake removals. 

  • A sharp edge or ridge formed by the intersection of two curved surfaces 

  • Buttocks, arse. 

flank

noun
  • The outermost strip of a road. 

  • 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 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. 

verb
  • 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 attack 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. 

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