board vs detrain

board

detrain

verb
  • to reduce one's training, particularly during the offseason, in preparation for a cycle of retraining. 

  • To exit from a train; to disembark 

  • to remove a passenger or passengers from a train; to evacuate passengers from a train. 

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