boarding vs clearance

boarding

noun
  • A penalty called for pushing into the boards. 

  • The riding of a skateboard. 

  • The act of people getting aboard a ship aircraft, train, bus, etc.; embarkation. 

  • The act of a sailor or boarding party attacking an enemy ship by boarding it. 

  • A structure made of boards. 

clearance

noun
  • The first disposal in a chain that leaves the area of a stoppage, or a disposal that leaves the area of a stoppage itself. 

  • The act of clearing or something (such as a space) cleared. 

  • A permission for a vehicle to proceed, or for a person to travel. 

  • A permission to have access to sensitive or secret documents or other information. 

  • The act of kicking a ball away from the goal one is defending. 

  • The act of potting all the remaining balls on a table at one visit. 

  • Clear or net profit. 

  • The settlement of transactions involving securities or means of payment such as checks by means of a clearing house. 

  • A permission to use something, usually intellectual property, that is legally, but not otherwise, protected. 

  • The height or width of a tunnel, bridge or other passage, or the distance between a vehicle and the walls or roof of such passage; a gap, headroom. 

  • The distance between two moving objects, especially between parts of a machine 

  • A sale of merchandise, especially at significantly reduced prices, usually in order to make room for new merchandise or updated versions of the same merchandise. 

  • The removal of harmful substances from the blood; renal clearance. 

  • Removal of pieces from a rank, file or diagonal so that a bishop, rook or queen is free to move along it. 

  • The act of leaving the area of a stoppage. 

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