masturbate vs wank off

masturbate

verb
  • To stimulate someone else sexually without penetration of the penis. 

  • To stimulate or please oneself by means of anything, not necessarily sexual, that does not get them anywhere; something that wastes their time; something that does not help others or achieve any important goal. 

  • To stimulate oneself sexually, especially by use of one’s hand or a sex toy made for this purpose, often to the point of ejaculation or orgasm. 

wank off

verb
  • To masturbate. 

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