hair extension vs plait

hair extension

noun
  • A length of hair which is attached to one's normal hair to make it longer. 

plait

noun
  • A braid, as of hair or straw; a plat. 

  • A flat fold; a doubling, as of cloth; a pleat. 

verb
  • To fold; to double in narrow folds; to pleat 

  • To interweave the strands or locks of; to braid 

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