hamper vs keep back

hamper

verb
  • To impede in motion or progress. 

  • To put into a hamper. 

  • To put a hamper or fetter on; to shackle 

noun
  • A wicker or plastic basket specifically for holding laundry (from clothes hamper), as opposed to a covered wicker basket which is a true hamper 

  • A shackle; a fetter; anything which impedes. 

  • A large basket, usually with a cover, used for the packing and carrying of articles or small animals 

  • A gift basket. 

  • Articles ordinarily indispensable, but in the way at certain times. 

keep back

verb
  • To prevent (a pupil) from advancing in a course. 

  • To hold back; to refuse to give or share. 

  • To restrict or restrain. 

  • To stay back; to refrain from approaching. 

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