principle vs rectitude

principle

noun
  • Moral rule or aspect. 

  • A fundamental essence, particularly one producing a given quality. 

  • A rule used to choose among solutions to a problem. 

  • A rule or law of nature, or the basic idea on how the laws of nature are applied. 

  • Bernoulli's Principle 

  • An original faculty or endowment. 

  • A fundamental assumption or guiding belief. 

  • A source, or origin; that from which anything proceeds; fundamental substance or energy; primordial substance; ultimate element, or cause. 

verb
  • To equip with principles; to establish, or fix, in certain principles; to impress with any tenet or rule of conduct. 

rectitude

noun
  • Conformity to the rules prescribed for moral conduct; (moral) uprightness, virtue. 

  • Straightness; the state or quality of having a constant direction and not being crooked or bent. 

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