pair of sunglasses vs sunglasses

pair of sunglasses

noun
  • A pair of glasses with tinted lenses designed to protect the eyes from sunlight. 

sunglasses

noun
  • Tinted glasses worn to protect the eyes from the sun. 

  • A person wearing sunglasses 

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