periphrasis vs tautology

periphrasis

noun
  • Expressing a grammatical meaning (such as a tense) using a syntactic construction rather than morphological marking. 

  • The substitution of a descriptive word or phrase for a proper name (a type of circumlocution). 

  • The use of a longer expression instead of a shorter one with a similar meaning, for example "I am going to" instead of "I will". 

  • The use of a proper name as a shorthand to stand for qualities associated with it. 

tautology

noun
  • Redundant use of words, a pleonasm, an unnecessary and tedious repetition. 

  • An expression that features tautology. 

  • A statement that is true for all truth values of its Boolean atoms. 

  • A statement that is true for all truth values of its propositional variables. 

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