hairdo vs ponytail

hairdo

noun

  • A hairstyle. 

  • A haircut. 

ponytail

noun

  • A hairstyle where the hair is pulled back and tied into a single "tail" which hangs down behind the head. 

verb

  • To form (the hair) into a ponytail. 

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