Walkman vs radiotelephone

Walkman

name
  • A street urchin. 

  • A Sony brand for personal portable audio media players 

  • A Sony portable personal compact cassette player product line 

radiotelephone

noun
  • a device that allows two-way communication via radio 

verb
  • To communicate via such a device 

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