certain vs plural

certain

adj
  • Known but not specifically named; indeterminate; indefinite; one or some; sometimes used independently as a noun, and meaning certain persons; see also "one". 

  • Unfailing; infallible. 

  • Fixed or stated; regular; determinate. 

  • Not to be doubted or denied; established as a fact. 

  • Sure, positive, not doubting. 

  • Actually existing; sure to happen; inevitable. 

det
  • Having been determined but not specified. 

pron
  • Unnamed or undescribed members (of). 

plural

adj
  • Consisting of or containing more than one of something. 

  • Pluralistic. 

  • In systems of number, not singular or not singular or dual. 

noun
  • A person with some form of multiplicity, particularly dissociative identity disorder. 

  • The plural number. In English, referring to more or less than one of something. 

  • A word in the form in which it potentially refers to something other than one person or thing; and other than two things if the language has a dual form. 

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