phenomenon vs portent

phenomenon

noun
  • A wonderful or very remarkable person or thing. 

  • An experienced object whose constitution reflects the order and conceptual structure imposed upon it by the human mind (especially by the powers of perception and understanding). 

  • A thing or being, event or process, perceptible through senses; or a fact or occurrence thereof. 

  • A knowable thing or event (eg by inference, especially in science) 

  • A kind or type of phenomenon (sense 1 or 2) 

  • A fact or event considered very unusual, curious, or astonishing by those who witness it. 

  • Appearance; a perceptible aspect of something that is mutable. 

portent

noun
  • Something regarded as portentous; a marvel; prodigy. 

  • A portending; significance 

  • Something that portends an event about to occur, especially an unfortunate or evil event; an omen. 

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