Question: "What is the definition of godspeed / god speed?"
Answer: The word godspeed (or god speed) comes from the Middle English god speid, a derivative of the phrase God spede you. Its first known use was in the 15th century. Godspeed is an expression of goodwill when someone is about to start a journey or venture on a daring endeavor. It is akin to saying, “I wish you good success” or “May God prosper you.”
The latter half of the compound word, speed, has nothing to do with swiftness; rather, the verb speed used to mean “to prosper or succeed.” Interestingly, the English word goodbye goes back to a contraction of “God be with ye” and carries a similar idea—God’s presence is wished for the person so that he will succeed and prosper. Comparable wishes for God’s blessings are also found in French (adieu) and Spanish (adios), whose farewell words literally mean “I commend you to God.”
The word God speed is found in only one passage in the Bible, and only in the King James Version: “If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed: For he that biddeth him God speed is partaker of his evil deeds” (2 John 1:10–11). Here John is warning believers against receiving false teachers or contributing to the success of anyone bearing a false gospel. To bid a false teacher “godspeed” is to express a wish for his success. Although we should love all people and desire their welfare, we cannot be faithful to the truth and at the same time wish the enemies of truth success in their endeavors. As John says, extending hospitality to a false teacher is to share in his work of falsehood.