Meaning

• To exit from a train; to disembark

  "If you plan to detrain at the next stop, please begin gathering your belongings."

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

  "Following the accident passengers were detrained through the rear cab."

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