In “The Story of An Hour,” by Kate Chopin, the author uses this word in the following sentence.

“He had only taken the time to assure himself of its truth by a second telegram, and had hastened to forestall any less careful, less tender friend in bearing the sad message.”

According to the merriam-webster dictionary, it means:

“to exclude, hinder, or prevent by prior occupation or measures”

This would mean that he quickly prevented any other friends from deliver the message of the death of her husband.