capital vs principal

capital

adj
  • Of prime importance. 

  • Of or relating to the head. 

  • Punishable by, or involving punishment by, death. 

  • used to emphasise greatness or absoluteness 

  • Chief, in a political sense, as being the seat of the general government of a state or nation. 

  • Uppercase. 

noun
  • A city designated as a legislative seat by the government or some other authority, often the city in which the government is located; otherwise the most important city within a country or a subdivision of it. 

  • Money and wealth. The means to acquire goods and services, especially in a non-barter system. 

  • Already-produced durable goods available for use as a factor of production, such as steam shovels (equipment) and office buildings (structures). 

  • The most important city in the field specified. 

  • An uppercase letter. 

  • The uppermost part of a column. 

  • Knowledge; awareness; proficiency. 

  • The chief or most important thing. 

principal

adj
  • Primary; most important; first level in importance. 

  • Chosen or assumed among a branch of possible values of a multi-valued function so that the function is single-valued. 

noun
  • The chief administrator of a school. 

  • A diapason, a type of organ stop on a pipe organ. 

  • The construction that gives shape and strength to a roof, generally a truss of timber or iron; or, loosely, the most important member of a piece of framing. 

  • A dancer at the highest rank within a professional dance company, particularly a ballet company. 

  • The primary participant in a crime. 

  • The first two long feathers of a hawk's wing. 

  • A security principal. 

  • A legal person that authorizes another (the agent) to act on their behalf; or on whose behalf an agent or gestor in a negotiorum gestio acts. 

  • The chief executive and chief academic officer of a university or college. 

  • The money originally invested or loaned, on which basis interest and returns are calculated. 

  • A partner or owner of a business. 

  • One of the turrets or pinnacles of waxwork and tapers with which the posts and centre of a funeral hearse were formerly crowned 

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