alternate vs principal

alternate

noun
  • A substitute; an alternative; one designated to take the place of another, if necessary, in performing some duty. 

  • A replacement of equal or greater value or function. 

  • A proportion derived from another proportion by interchanging the means. 

  • That which alternates with something else; vicissitude. 

  • Figures or tinctures that succeed each other by turns. 

adj
  • Other; alternative. 

  • Distributed singly at different heights of the stem, and at equal intervals as respects angular divergence 

  • Designating the members in a series, which regularly intervene between the members of another series, as the odd or even numbers of the numerals; every other; every second. 

  • Happening by turns; one following the other in succession of time or place; first one and then the other (repeatedly) 

verb
  • To vary by turns. 

  • To perform by turns, or in succession; to cause to succeed by turns; to interchange regularly. 

  • To perform an alternation (removal of alternate vertices) on (a polytope or tessellation); to remove vertices (from a face or edge) as part of an alternation. 

  • To happen, succeed, or act by turns; to follow reciprocally in place or time; followed by with. 

principal

noun
  • 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 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. 

  • 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 

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

  • Primary; most important; first level in importance. 

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